Packaging Receptacle For Making Packaging Article Exhibiting Combination of Linear Tear and Directional Curl

ABSTRACT

A packaging receptacle, made from a flexible film, has a first side sealed to a second side, a top edge and an open top, an interior chamber, and a tear initiator. A product is placed in the internal chamber within the packaging receptacle, and the receptacle sealed closed. The flexible film has a linear tear property and an imbalanced internal stress so that the film exhibits a linear tear property in combination with the torn edges curling outwardly and away from the interior chamber within the packaging article. The packaging receptacle is particularly suited for the packaging of medical products to be sterilized while in the package. Also disclosed is a manually-openable packaged product, a process for preparing and transferring a product, and a process of opening a packaged product made from a packaging receptacle.

FIELD

The invention is directed to the packaging of products that benefit from low exposure to contamination, and particularly to products that are either sterile at the time of packaging or sterilized while in the package, with the package to be opened and the sterile product therein removed in sterile condition.

BACKGROUND

Various types of packaging articles have been used to package products which are sterile and/or are to be sterilized. Such products include surgical drapes, gowns, and gloves, surgical instruments, implements, and kits, surgical equipment and hardware, medical implants, and other medical devices Packaging articles that have been used for packaging sterile (or to-be-sterilized) medical articles include double entry trays, double entry pouches, double entry trays inside a pouch, single entry trays, single entry pouches, header bags, and central sterile reprocessing wrap (“CSR wrap”).

These various types of packaging articles have also been used to package non-medical products such as laboratory and research equipment, testing equipment, etc., which are also sterile and/or to be sterilized. Such articles may be used in research and development, analytical procedures, medical end uses, etc. Such articles include, for example, sample containers, Petri dishes, and laboratory equipment.

Header bags are bags having a “header” portion extending outward of a heat seal. Of the various types of packaging articles above, header bags made from flexible films have been found to be a less-preferred type of package for the packaging of medical articles. Header bags for packaging of articles to be sterilized while in the bag frequently have a gas-permeable “header strip,” and/or a plurality of gas-permeable vents therein. Hospital workers have cited the header bag opening fixture as causing recurrent and/or significant use issues.

Some of the header bags have a Tyvek® spun bonded high density polyethylene fiber breathable header strip that is permeable with respect to ethylene oxide gas used during the product sterilization procedure. This header strip is sealed to the closed end of the bag. Bags having the Tyvek® header present challenges in sterilizing, as the Tyvek® header strip may not allow for the contents to receive ethylene oxide gas in sufficient quantity throughout the package interior to result in sterilization of the entire interior of the package and the entire product within the package. Bags having a Tyvek® spun bonded high density polyethylene fiber header also exhibit seal failures as the product contacts the Tyvek®-to-film seal, resulting in “seal creep.” In addition, the peeling open of the seal in the header bags with the header strip can result in tearing of the fibrous material and the emission of particulates, and requires post-peel seal inspections to determine the integrity of the seals.

Moreover, bags having headers made from Tyvek® spun bonded high density polyethylene fiber have historically been an area of complaint from nurses and hospital workers for the additional reason that these header bags have been difficult to open. Such header bags typically have a small thumb notch and a small grip area. Presentation of the product in the package is difficult because the excess material is difficult to clear away during the peeling open of the package.

In a hospital environment, particularly in the surgical arena, it is common to package medical supplies and devices and thereafter sterilize the inside of the packaging article as well as the product inside the package. The sterilized package is thereafter handled and opened by a “non-sterile nurse”. The non-sterile nurse opens the package in a manner such that the contents are presented to a “sterile nurse” without the article coming into contact with a non-sterile surface or other non-sterile contaminant. More particularly, during opening of the package, the non-sterile nurse must be careful not to allow the article inside the package to contact any non-sterile surface, including the exterior surface of the package being opened, any portion of the non-sterile nurse, or any other non-sterile surface. The transfer of the sterile article by the non-sterile nurse to the sterile nurse is followed by the manual possession of the article by the sterile nurse, who must take care not to contact the exterior surface of the package while also taking care to ensure that the product does not contact the exterior surface of the package or any other non-sterile surface. In the event that the product or the sterile nurse contacts the outside surface of the package or any other non-sterile surface, the article is considered to be potentially contaminated, and must be discarded or recycled and re-sterilized.

Operating room nurses have indicated that packages made from header bags are among the least liked of all the package types used for sterile presentation and sterile transfer. Packages made from header bags have caused difficulties with sterile presentation for operating room nurses and emergency room nurses, in that they are difficult and cumbersome to open, and after opening, sterile presentation and sterile transfer of the product is difficult. Moreover, header bags need to be inspected for leaks that could have contaminated the interior of the package and the contents of the package. Furthermore, these header bags have exhibited less than optimal performance with respect to ensuring sterile presentation and sterile transfer from the non-sterile nurse to the sterile nurse. There are at least three reasons for the less than optimal performance of the sterile presentation and sterile transfer.

The first reason is the difficulty of opening the package. The difficulty may be due to the small grip area and no grip assister, or a grip assister that is too small. The need for the use of an opening implement such as scissors or a sharp blade, and/or the need for the use of substantial manual force to open, increases the probability of contamination of the product during the opening of the package. The second reason is that during opening of the package, the flexible film can inadvertently “fold back” so that the exterior surface of the package inadvertently contacts the product inside, resulting in potential contamination of the product. The third reason is the difficulty of opening the package in a manner to expose enough of the sterile product that the sterile nurse can readily take the product with low risk of contacting the exterior surface of the package.

SUMMARY OF THE INVENTION

A first aspect is directed to a packaging receptacle for making a manually-openable package for packaging a product. The packaging receptacle is made from a flexible film. The packaging receptacle comprises (a) a first side sealed to a second side at a first seal, (b) a top edge and an open top so that the product can be inserted into an interior chamber within the packaging receptacle, and (c) a tear initiator. The flexible film has both a linear tear property and an imbalanced internal stress. Upon placing a product into the packaging receptacle and sealing the packaging receptacle closed with a top seal to form a packaging article around the product, the tear initiator is present in a skirt which is outward of the first seal or outward of the top seal. Upon manually initiating a tear from the tear initiator, the tear is manually propagated through the first seal or the top seal. The tear thereafter further propagates as both a first tear and a second tear. The first tear is down the first side of the packaging article and the second tear is down the second side of the packaging article. The manual propagation of the tear down the first side produces first and second torn edges. The manual propagation of the tear down the second side produces third and fourth torn edges. The film along at least the first torn edge and the second torn edge curls outwardly and away from the interior chamber within the packaging article, i.e., curls away from the product.

The film from which the packaging receptacle is made can have a total free shrink at 85° C. of less than 10 percent, measured in accordance with ASTM D2732. Alternatively, the packaging receptacle can have a total free shrink at 185° F. of from 11 percent to 120 percent measured in accordance with ASTM D2732; or from 20 percent to 100 percent at 185° F. measured in accordance with ASTM D2732; or from 30 percent to 90 percent at 185° F. measured in accordance with ASTM D2732.

The tear initiator can be positioned so that the first and second tears are made along parallel lines, with the distance between the first and second tear lines being from 0.125 to 6 inches.

The film can be a multilayer film. At least one layer of the multilayer film can be a layer that imparts the linear tear property to the film. The layer that imparts the linear tear property to the film can comprise a blend that makes up at least 51 percent of the layer weight. The blend can comprise at least one member selected from the group consisting of (i) low density polyethylene and ionomer resin, (ii) polybutylene and ionomer resin, (iii) ethylene/vinyl acetate copolymer and ionomer resin, (iv) linear low density polyethylene and ionomer resin, (v) low density polyethylene and styrene/butadiene copolymer, (vi) low density polyethylene and polybutylene, (vii) cyclic olefin copolymer and low density polyethylene, (viii) cyclic olefin copolymer and linear low density polyethylene, (ix) cyclic olefin copolymer and high density polyethylene, (xi) cyclic olefin copolymer and polypropylene, (x) cyclic olefin copolymer and polystyrene, (xi) cyclic olefin copolymer and styrene/butadiene copolymer, (xii) polybutylene and ethylene/vinyl acetate copolymer, (xiii) polybutylene and linear low density polyethylene, (xiv) polybutylene and high density polyethylene, (xv) ethylene/vinyl acetate copolymer and linear low density polyethylene.

The packaging receptacle can be made from a multilayer film comprising a linear tear layer, a curl layer, and a seal layer. The linear tear layer can provide the multilayer film with the linear tear property, with the linear tear layer making up from 50 to 70 percent of the total film thickness. The incompatible polymer blend can make up from 80 to 100 weight percent of the linear tear layer, or from 90 to 100 weight percent; or from 95 to 100 weight percent. The curl layer provides the film with the imbalance of internal stress, and can make up from 15 to 35 percent of the total film thickness, or from 15 to 30 percent, or from 15 to 25 percent. The curl layer can comprise at least one member selected from the group consisting of high density polyethylene, styrene/butadiene copolymer, polystyrene, ethylene/norbornene copolymer, polyamide, polyester. The seal layer is an outer layer and can comprise at least one member selected from the group consisting of ethylene homopolymer, ethylene/alpha-olefin copolymer, ionomer resin, and ethylene/unsaturated ester copolymer, with the outer heat-sealable layer having a thickness of at least 5 percent of the total film thickness.

Upon tearing the packaging article open, the third and fourth torn edges can also curl away from the interior chamber within the packaging article.

In the packaging receptacle, the skirt can be outward of the first seal, with the tear initiator being present in the skirt.

In the packaging receptacle, the skirt can be outward of the top seal, with the tear initiator is present in the skirt.

The packaging receptacle can be sealed closed with the first and second tears thereafter being propagated down the length of the packaging article to an opposite edge of the packaging article.

At least one lay-flat side of the packaging receptacle can further comprise a vent having a continuous film edge defining a vapor passageway into the interior of the packaging receptacle, with a semi-permeable membrane covering the vapor passageway. The semi-permeable membrane can overlap the film in a rim region around the passageway, with the semi-permeable membrane being bonded to the film around an entirety of a perimeter of the passageway. The vent can be positioned so that neither the first tear down the first lay-flat side of the article nor the second tear down the second lay-flat side of the packaging article propagates into or through the vent.

The semi-permeable membrane can comprise a spun-bonded high density polyethylene fibrous sheet. The film can be heat sealed to the semi-permeable membrane.

The packaging receptacle can comprise a first vent and a second vent, with the first vent being separated from the second vent by a distance of from 5 centimeters to 50 centimeters, or 7 to 35 centimeters, or 10 to 25 centimeters, or 10 to 20 centimeters.

The packaging receptacle can further comprise a third vent and a fourth vent, with each of the first, second, third, and fourth vents being separated from the other vents by a distance of at least 2 centimeters, or 7 to 35 centimeters, or 10 to 25 centimeters, or to 20 centimeters.

The packaging receptacle can further comprise a first grip-assister on a first side of the tear initiator and a second grip-assister on a second side of the tear initiator, each of the first and second grip assisters comprising a continuous interior film edge defining a passageway through the skirt of the packaging receptacle. The packaging receptacle can further comprise third and fourth grip assisters, with the first grip assister being coincident with the third grip assister, and the second grip assister being coincident with the fourth grip assister. One, all, or any subset of the grip assisters can have a hanging chad therein.

The packaging receptacle can be in the form of an end-seal bag comprising a seamless film tubing in lay-flat configuration with the first seal being a first heat seal forming a bottom of the interior chamber within the end-seal bag. The end-seal bag has a folded first side edge and a folded second side edge. Upon placing a product into the end-seal bag and sealing the end-seal bag closed with the top heat seal, the end-seal bag forms a packaging article around the product, with the tear initiator being present in the skirt which is outward of the first heat seal, or in a skirt outward of the top heat seal. Upon manually initiating a tear from the tear initiator, the tear can be manually propagated through the first heat seal or the top heat seal, with the tear thereafter further propagating as both the first tear and the second tear. The first tear is down the first lay-flat side of the packaging article and the second tear being down the second lay-flat side of the packaging article. The manual propagation of the tear down the first lay-flat side produces first and second torn edges, and the manual propagation of the tear down the second lay-flat side produces third and fourth torn edges. Film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article. One or more tear initiators can be present in the skirt outward of the first heat seal.

The packaging receptacle can be in the form of a side-seal bag comprising a flat film having a folded bottom edge, with the film on a first side of the fold making up the first lay-flat side of the side-seal bag and the film on a second side of the fold making up the second lay-flat side of the side-seal bag. The first seal is a first side seal along a first side edge of the bag and is a heat seal. The first side seal extends from the folded bottom edge of the side-seal bag to the top edge of the side-seal bag. The side-seal bag further comprising a second side seal along a second side edge of the bag. The second side seal is also a heat seal. The second side seal extends from the folded bottom edge of the side-seal bag to the top edge of the side-seal bag. Upon placing a product into the side-seal bag and sealing the side-seal bag closed with the top seal, the side-seal bag forms a packaging article around the product. The tear initiator is present in the skirt which is (i) outward of the first side seal or (ii) outward of the second side seal, or (iii) outward of the top seal. Upon manually-initiating a tear from the tear initiator, the tear can be manually-propagated through the respective first heat seal or the second heat seal or through the top seal, with the tear thereafter further propagating as both the first tear and the second tear. The first tear is down the first lay-flat side of the packaging article and the second tear is down the second lay-flat side of the packaging article. The manual propagation of the tear down the first lay-flat side producing first and second torn edges. The manual-propagation of the tear down the second lay-flat side producing third and fourth torn edges. Film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.

The packaging receptacle can be in the form of an L-seal bag comprising a flat film having a fold therein, with the fold providing a first side edge of the L-seal bag, with the film on a first side of the fold making up the first lay-flat side of the L-seal bag and the film on a second side of the fold making up the second lay-flat side of the L-seal bag. The fold extends from a bottom edge of the L-seal bag to the top edge defining the open top of the L-seal bag. The first seal is a heat seal which is an end seal forming a bottom of the interior chamber of the L-seal bag. The first heat seal is along a bottom edge of the L-seal bag. The first heat seal extends from the first side edge of the L-seal bag to the second side edge of the L-seal bag. The L-seal bag further comprises a second heat seal along a second side edge thereof. The second heat seal extends from the bottom edge of the L-seal bag to the top edge of the L-seal bag. Upon placing a product into the L-seal bag and sealing the L-seal bag closed with the top seal, the L-seal bag forms a packaging article around the product. The tear initiator is present in: (i) the skirt which is outward of the first heat seal, or (ii) the second heat seal, or (iii) the top seal. Upon manually-initiating a tear from the tear initiator, the tear can be manually-propagated through the respective first heat seal or second heat seal or top seal. The tear can thereafter further propagate as both the first tear and the second tear. The first tear is down the first lay-flat side of the packaging article, and the second tear is down the second lay-flat side of the packaging article. The manual propagation of the tear down the first lay-flat side produces first and second torn edges, while the manual propagation of the tear down the second lay-flat side produces third and fourth torn edges. Film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.

In the L-seal bag, the skirt can be a first skirt which is outward of the first heat seal, with the tear initiator being a first tear initiator present in the first skirt, with the L-seal bag further comprising a second skirt outward of the second heat seal, with a second tear initiator in the second skirt. The second tear initiator can be in a position to make a linear tear along the top heat seal of the packaging article, so that upon initiating first and second linear tears across the first and second lay-flat sides of the packaging article from the second tear initiator to the opposite edge of the packaging article, with the first and second tears being manually-propagated across a width of the packaging article, and thereafter initiating third and fourth linear tears down the first and second lay-flat sides of the packaging article from the first tear initiator, with the third and fourth tears being manually-propagated down the length of the packaging article to the opposite edge of the packaging article, a first unrestrained corner flap is produced on the first lay-flat side of the packaging article, and a second unrestrained corner flap is produced on the second lay-flat side of the packaging article. The unrestrained corner flaps can curl all the way back to a diagonal line extending from a torn end of the first heat seal to a torn end of the second heat seal, thereby exposing the product within the chamber of the packaging article. By providing the tear initiators at diagonally opposite corners of the L-seal bag, the order of making the tears does not matter.

The packaging receptacle can be in the form of a pouch, in which the first lay-flat side is a discrete first film panel and the second lay-flat side is a discrete second film panel. The first seal is a heat seal which is an end seal forming a bottom of the interior of the packaging receptacle. The end seal extends along a bottom edge of the pouch, from a first side edge of the pouch to a second side edge of the pouch. The pouch further comprising a second heat seal along a first side edge of the pouch. A second heat seal extends from the bottom edge of the pouch to the top edge of the pouch that defines the open top of the pouch. The pouch further comprises a third heat seal along a second side edge of the pouch. The third heat seal also extends from the bottom edge of the pouch to the top edge of the pouch. Upon placing a product into the pouch and sealing the pouch closed with the top seal, the pouch bag forms a packaging article around the product, with the tear initiator being present in the skirt which is outward of (i) the first heat seal, or (ii) the second heat seal (iii) the third heat seal, or (iv) the top seal. Upon manually initiating a tear with the tear initiator being present in the skirt which is outward of the first heat seal, the second heat seal, the third heat seal, or the top heat seal, the tear can be manually propagated through the respective seal, with the tear thereafter further propagating as both the first tear and the second tear. The first tear is down the first lay-flat side of the pouch and the second tear is down the second lay-flat side of the pouch. The manual propagation of the tear down the first lay-flat side produces first and second torn edges, and the manual propagation of the tear down the second lay-flat side producing third and fourth torn edges. Film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.

In the pouch, the skirt can be a first skirt which is outward of the first heat seal, and the tear initiator can be a first tear initiator present in the first skirt. The pouch can further comprise a second skirt outward of the second heat seal, with a second tear initiator in the second skirt. The second tear initiator can be in a position to make a linear tear along the top heat seal of the packaging article. Upon initiating first and second linear tears across the first and second lay-flat sides of the packaging article from the second tear initiator to the opposite edge of the packaging article, with the first and second tears being manually-propagated across a width of the packaging article, and thereafter initiating third and fourth linear tears down the first and second lay-flat sides of the packaging article from the first tear initiator, with the third and fourth tears being manually-propagated down the length of the packaging article to the opposite edge of the packaging article, a first unrestrained corner flap is produced on the first lay-flat side of the packaging article, and a second unrestrained corner flap is produced on the second lay-flat side of the packaging article. The unrestrained corner flaps are capable of curling all the way back to a diagonal line extending from a torn end of the first heat seal to a torn end of the second heat seal, thereby exposing the product within the chamber of the packaging article. By providing the tear initiators at diagonally opposite corners of the pouch, the order of making the tears does not matter.

The film can be a monolayer film or a multilayer film.

The film can have a thickness of from 1 mil to 20 mils, or from 1.5 mils to 10 mils, or from 2 mils to 6 mils, or from 2 mils to 4 mils.

A second aspect is directed to a manually-openable packaged product comprising a packaging article having a product within. The packaging article made from a packaging receptacle in accordance with the first aspect of the invention, described above. The product can be (i) a product to be sterilized, or (ii) a sterilized product, or (iii) a product which can be sterile or non-sterile, but which is to be removed from the packaging article with minimal chance of the addition of contamination to the product (e.g., a food product, etc).

A third aspect is directed to a process for preparing and transferring a sterile medical product from a non-sterile nurse to a sterile nurse. The process comprises: (1) providing a packaging receptacle in accordance with the first aspect of the invention, described above; (2) placing a medical product (which can be sterile or non-sterile) through the open top of the packaging receptacle and into an interior chamber within the packaging receptacle; (3) sealing the packaging receptacle closed with the non-sterile medical product inside, by making a top seal of the side of the packaging receptacle to the second side of the packaging receptacle to close the open top, whereby a packaged product is formed with the medical product inside a packaging article; (4) if the product is not sterile when placed in the packaging receptacle, subjecting the packaged product to a sterilizing procedure to sterilize the product while it is within the packaging article; (5) transporting, to a desired location, the packaged product containing the sterile product within the packaging article; (6) opening the packaging article by manually-initiating and manually-propagating a tear from a tear initiator in the packaging article, with the tear being propagated through the skirt and through the a seal along an edge of the skirt, with the tear thereafter further propagating as both a first tear and a second tear, the first tear being down a first side of the packaging article and the second tear being down a second side of the packaging article, with the propagation of the tear down the first lay-flat side producing first and second torn edges, and the propagation of the tear down the second lay-flat side producing third and fourth torn edges, with a first portion of the packaging article outward of the first and third torn edges being a first torn portion of the packaging article, and a second portion of the packaging article outward of the second and fourth torn edges being a second torn portion of the packaging article, with the flexible film having a linear tear property and an imbalanced internal stress oriented so that the film outward of the first torn edge and the film outward of the second torn edge curl outwardly and away from the interior of the packaging article, with the tears being manually-propagated to an extent that the product is exposed and can readily be removed while film along the first and third torn film edges curls outward and away from the product.

A fourth aspect is directed to a process of (a) providing a packaging receptacle having an open top and a tear initiator, the packaging receptacle being made from a film having a linear tear property and an imbalanced internal stress oriented so that the film curls towards an outer surface of the packaging article upon tearing; (b) placing a product in the packaging article; (c) sealing the packaging receptacle closed to form a packaging article containing the product; (d) manually-initiating and manually-propagating first and second tears from the tear initiator so that the packaging article is torn open and at least two torn edges of the packaging article curl outward away from the product and away from an internal chamber within the packaging article.

The second, third, and fourth aspects of the invention can utilize the various features described above for the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic of an end-seal packaging receptacle in accordance with the invention.

FIG. 1B is an enlarged schematic view of the header portion of the packaging receptacle of FIG. 1A, providing an enlarged view of the tear initiators and grip assisters.

FIG. 1C is an enlarged perspective view of a vent portion of the packaging receptacle of FIG. 1C.

FIG. 1D is a perspective view of a package made from the packaging receptacle of FIG. 1A, the package having a product within a packaging article, with the packaging article having been manually torn along a portion of the length thereof, with the film curling away from the product inside the packaging article.

FIG. 1E is a perspective view of comparative package in which the packaging article has been made from an end-seal packaging receptacle of FIG. 1A, with torn edges of the film remaining flat after tearing, i.e., not curling away from the product within the packaging article.

FIG. 2 is a schematic of a first embodiment of a side-seal packaging receptacle in accordance with the invention.

FIG. 3 is a schematic of a second embodiment of a side-seal packaging receptacle in accordance with the invention.

FIG. 4 is a schematic of an L-seal packaging receptacle in accordance with the invention.

FIG. 5 is a schematic of a first embodiment of a pouch-type packaging receptacle in accordance with the invention.

FIG. 6 is a schematic of a second embodiment of a pouch-type packaging receptacle in accordance with the invention.

FIG. 7 is a schematic of an alternative end-seal packaging article in accordance with the invention.

FIG. 8 is a schematic of a prior art packaged product.

FIG. 9 is a schematic of one embodiment of a process for making a flexible thermoplastic film to be used in a packaging article of the invention.

DETAILED DESCRIPTION

The packaging article of the present invention can be designed for the packaging of one or more products that are to be sterilized after being placed into the packaging article. After the product is placed into the packaging article, the article is hermetically closed, for example by heat sealing. After the packaging article is closed, if it is desired to subject the product to sterilization using, for example, ethylene oxide gas, the packaging article can be provided with one or more vents to allow the ethylene oxide gas to move into and throughout the package in order to sterilize both the product and the packaging article.

Once the packaging article is removed from the ethylene oxide gas environment, the product and the interior of the packaging article are sterile, but the exterior surface of the package is no longer sterile if it is exposed to a non-sterile environment. Ethylene oxide is a cyclic ether and is a gas at room temperature and pressure. Ethylene oxide is also referred to as “EtO” and “oxirane.” Ethylene oxide has the formula C₂H₄O.

The packaging article need not be provided with one or more vents and the product sterilized while in the package. For example, sterilization can be conducted using gamma irradiation or electron-beam irradiation.

The packaging article is designed with a manual tear feature to improve the ease of opening the package and to improve the sterile presentation and sterile transfer for use in hospital and laboratory environments. The manual tear feature allows the packaging article to be opened via manual tearing, without the use of opening implements such as scissors or a knife. However, the manual tear feature is also designed to prevent unintended tearing that would produce a likelihood of unintended loss of sterility of the product and/or the packaging article.

The manual tear feature is also designed to allow the packaging article to be torn in a manner that provides various advantages. More particularly, the manual tear feature allows the packaging article to be readily torn along its length so that a substantial portion of the product inside the packaging article is not inside the packaging article and is not covered by the packaging article. The resulting high quality presentation provides exposure of enough of the product to enable the sterile nurse to readily grab and pull the product from the torn packaging article without having to take great care to avoid touching any non-sterile portion of the packaging article, such as the outside surface of the packaging article. Moreover, the easy tear package can be opened with a tear that is extensive enough that the product can be readily removed from the package without the extra time, effort, and difficulty associated with “manipulating” the package in order to remove it from the torn packaging article.

Optionally, the manual tear packaging article of the invention can be provided with high strength seals to provide improved package integrity over peel-open packaging articles that utilize peel apart seals. Such high strength seals are not peelable, and accordingly have less likelihood of having a seal defect, or an accidental seal peel during handling, either of which compromise the sterility of the product as well as compromising the sterility of the interior surface of the packaging article.

Peel-open packages containing sterile products, particularly packages utilized in emergency rooms and surgical procedures, call for the inspection of the peelable seals after peeling, to ensure that the sterility of the package interior and/or the package contents are not compromised. In contrast, at least some embodiments of the manual tear packaging article of the invention provided with high strength seals require no such seal inspections because manual tearing, rather than peeling of the seal, is used to open the packaging article. This advantage improves efficiency in emergency rooms and operating rooms.

At least some embodiments of the tear-open packaging article of the invention can utilize relatively inexpensive components. These embodiments can therefore provide more cost-effective packaging. Such lower-cost packaging is especially suited to the packaging of lower cost medical items such as surgical gowns, drapes, and gloves.

At least some embodiments of the tear-open packaging article of the invention can be designed to offer at least two advantages over at least some of the packaging articles comprising a Tyvek® spun bonded high density polyethylene fiber breathable header strip. In the marketplace today, at least some of the packaging articles comprising a Tyvek® spun bonded high density polyethylene fiber breathable header strip are opened by peeling the seal between the flexible plastic film and the Tyvek® spun bonded high density polyethylene fiber breathable header strip. Making a hermetic heat-seal of Tyvek® spun bonded high density polyethylene fiber breathable header strip to a heat seal layer of a plastic film can be more difficult than heat sealing one seal layer of a plastic film to itself or to another heat seal layer of another plastic film. As such, the heat seal of the Tyvek® spun bonded high density polyethylene fiber breathable header strip to a heat seal layer of a plastic film generally results in a higher probability of seal defect or seal failure versus a heat seal of a seal layer of a plastic film to itself or to another heat seal layer of another plastic film. Thus, at least some embodiments of the tear-open packaging article of the invention can provide the advantage of lower seal defects and lower seal failures, relative to peel-apart packages that comprise a peelable seal between a flexible plastic film and a Tyvek® spun bonded high density polyethylene fiber breathable header strip.

Second, the opening of at least some packages comprising a peelable seal between a flexible plastic film and a Tyvek® spun bonded high density polyethylene fiber breathable header strip, can produce fiber tearing with the possible (or even probable) release of particulate material in the form of short fibers, broken portions of fibers, and/or other particulates present in a film coating or any other release of particulate material during the peeling of the fibrous strip from the film to which it is heat sealed. The release of most particulate materials is undesirable in an environment in which an objective is the sterile presentation and sterile transfer of the product inside the package.

Third, although the commercially available packaging articles that comprise a Tyvek® spun bonded high density polyethylene fiber breathable header strip permit ingress and egress of a sterilizing gas, such as EtO, once the product is placed into the packaging article and the article sealed closed and the resulting packaged product placed into a sterilization chamber, the sterilizing gas may not sterilize the entire interior surface of the packaging article, as well as the entirety of the contents of the packaging article (including any gas present in the packaging article), because the sterilizing gas does not permeate the entire package in the time the packaged product is in the sterilization chamber. Generally, the header strip is at one end of the package. Factors that affect the adequacy of the sterilization include (i) the size of the package, (ii) the size of the header strip, and (iii) the location of the header strip. At least some embodiments of the packaging article of the invention include a plurality of discrete breathable vents at various locations throughout the packaging article in order to improve the ingress of sterilization gas throughout the entire interior volume within the package to ensure the complete sterilization of the product, the interior surface of the packaging article, and any gas or liquid within the package.

Relative to at least some other packaging articles in current commercial use for the packaging of sterile products and/or products to be sterilized while in the package, at least some embodiments of the packaging article of the present invention are of less bulk, than these other packaging articles. These other packaging articles include one or more of the following types of articles: double entry trays, double entry pouches, double entry trays inside a pouch, single entry trays, single entry pouches, header bags, and CSR wrap.

For example, for at least some embodiments of the packaging article of the invention, over 90 percent of the weight of the packaging article is a flexible film having a thickness of 5 mils or less. At least some embodiments of the packaging article of the invention contain from 0.1 to 10 weight percent of one or more vents made from Tyvek® spun bonded high density polyethylene fiber or other suitable material. The result of reduced package bulk is reduced freight cost, reduced manufacturing cost, and greater sustainability via material source reduction.

Relative to at least some other packaging articles in current commercial use for the packaging of sterile products and/or products to be sterilized while in the package, at least some embodiments of the packaging article of the present invention are suited to the packaging of a wide variety of different sterile products or different products to be sterilized. These embodiments of the packaging articles of the invention provide a total systems packaging solution.

Relative to at least some other packaging articles in current commercial use for the packaging of sterile products and/or products to be sterilized while in the package, at least some embodiments of the packaging article of the present invention can be made using production machinery currently in commercial use for making other products. In such instances, lower volume production runs become more feasible from an economic viewpoint. Moreover, manufacture of at least some embodiments of the packaging article of the invention can be carried out using production machinery and processing in current commercial use for the production of heat-shrinkable films.

Relative to at least some other packaging articles in current commercial use for the packaging of sterile products and/or products to be sterilized while in the package, at least some embodiments of the packaging article of the present invention can be sealed closed using packaging machinery currently in commercial packaging other products. These advantages of at least some packaging articles according to the invention increase the efficiency of transitioning to the manufacture and use of at least some of the packaging articles of the present invention. For example, at least some embodiments of the packaging article of the present invention can be sealed closed with a heat sealing apparatus which is an impulse bar sealer or a vacuum sealer.

As used herein, the term “film” is inclusive of plastic web, regardless of whether it is film or sheet. The film can have a total thickness of 0.25 mm or less, or a thickness of from 1.5 mils to 10 mils, or from 2 to 5 mils, or from 2.5 mils to 4.5 mils, or from 3 mils to 4 mils.

The film from which the packaging receptacle is made can have a Peak Load Impact Strength, determined using ASTM D 3763-95A, of at least 50 Newtons per mil. ASTM D 3763-95A is hereby incorporated, in its entirety, by reference thereto. The film can have a Peak Load Impact Strength, determined using ASTM 3763-95A, of from 50 to 250 Newtons per mil, or from 60 to 200 Newtons per mil, or from 70 to 170 Newtons per mil; or from 80 to 150 Newtons per mil; or from 85 to 140 Newtons per mil; or from 95 to 135 Newtons per mil. In one embodiment, the film can exhibit a Peak Load Impact Strength, determined using ASTM D 3763-95A, of from 50 to 250 Newtons per mil, and the film can have a total thickness of from 1.5 mils to 5 mils.

The multilayer film can have a seal layer and at least one additional layer. At least one layer of the multilayer film can contain a blend of incompatible polymers.

As used herein, the phrase “machine direction” refers to the direction in which the film emerges from the die. Of course, this direction corresponds with the direction the extrudate is forwarded during the film production process. The phrase “machine direction” corresponds with “longitudinal direction”. Machine direction and longitudinal direction are abbreviated as “MD” and “LD”, respectfully. However, as used herein, the phrase “machine direction” includes not only the direction along a film that corresponds with the direction the film traveled as it passed over idler rollers in the film production process, it also includes directions that deviate up to 44 degrees from the direction the film traveled as it passed over idler rollers in the production process.

As used herein, the phrase “transverse direction” refers to a direction perpendicular to the machine direction. Transverse direction is abbreviated as “TD”. The transverse direction also includes directions that deviate up to 44 degrees from the direction the film traveled as it passed over idler rollers in the production process.

As used herein, the phrase “packaging receptacle” is inclusive end-seal bags, side-seal bags, L-seal bags, U-seal bags (also referred to as “pouches”), T-seal bags (made from a single piece of film folded so as to provide two folded side edges, an open top, a bottom seal, and a backseam seal that is a fin-seal or lap-seal, with the backseam forming a “T” with the bottom seal), gusseted bags, backseamed tubings, and seamless casings, as well as packages made from such articles by placing a product in the article and sealing the article to form a packaging article surrounding the product. As used herein, packaging articles have two “sides”. Generally, a “side” of a packaging receptacle corresponds with half of the article. For example, an end-seal bag is a lay-flat bag and has two sides (in this case two lay-flat sides), with each side corresponding with a lay-flat side of the seamless tubing from which the end-seal bag is made. Each lay-flat side of a seamless tubing is bounded by the creases formed as the tubing is collapsed into its lay-flat configuration between nip rollers. Each side of an end-seal bag is bounded by the bag top edge, the bag bottom edge, and the two tubing creases running the length of the bag. Likewise, a side-seal bag also has two sides, with each side also being a lay-flat side, with each side of the side-seal bag being bounded by bag side edges, a bag top edge, and a bag bottom corresponding with a tubing crease. A casing, whether seamless or backseamed, also has two sides, with each side being bounded by the ends of the casing and by creases formed as the casing is configured into its lay-flat configuration. Although gusseted bags and other packaging articles are not fully lay-flat in their structure because they have more than two flat sides, they nevertheless have “sides” bounded by creases and edges, and they nevertheless can be folded into a flat configuration.

As used herein, the term “package” refers to packaging materials configured around a product being packaged. As such, the term “package” includes all of the packaging around the product, but not the product itself.

As used herein, the phrase “packaged product” refers to the combination of a product and the packaging article that surrounds or substantially surrounds the product. The packaged product can be made by placing the product into a packaging receptacle made from the film exhibiting both the linear tear property and the imbalanced internal stress that provides curl, with the article then being sealed closed so that the multilayer film surrounds or substantially surrounds the product.

As used herein, the term “bag” refers to a packaging article having an open top, side edges, and a bottom edge. The term “bag” encompasses lay-flat bags, pouches, casings (seamless casings and backseamed casings, including lap-sealed casings, fin-sealed casings, and butt-sealed backseamed casings having backseaming tape thereon). Various casing configurations are disclosed in U.S. Pat. No. 6,764,729 B2, to Ramesh et al, entitled “Backseamed Casing and Packaged Product Incorporating Same, which is hereby incorporated in its entirety, by reference thereto. Various bag configurations, including L-seal bags, backseamed bags, and U-seal bags (also referred to as pouches), are disclosed in U.S. Pat. No. 6,970,468, to Mize et al, entitled “Patch Bag and Process of Making Same”, which is hereby incorporated, in its entirety, by reference thereto. While the bag configurations illustrated in the '468 patent have a patch thereon, for purposes of the present invention, the patch is optional.

End-seal bags, side-seal bags, L-seal bags, T-seal bags (also referred to as backseamed bags), and U-seal bags all have an open top, closed sides, a closed bottom, and at least one heat seal. Each of these heat seals is referred to as a “factory seal” because these seals are made in a bag-making factory, rather than in a packaging factory where the bag is used to package a product. Each of the factory seals is generally made a short distance inward of the edge of the article, so that a relatively small amount of film remains outward of the heat seal, i.e., on the other side of the seal from the film that envelopes the product. A gusseted bag can also be made with a bottom seal that has a skirt, and a casing (backseamed or seamless) can have a transverse heat seal with a skirt. As used herein, the term “skirt” refers to that portion of the film that is outward of any one or more of the factory seals. The “length” of a skirt is the distance corresponding to the length of the seal inward of the skirt, and the “width” of the skirt is the distance taken perpendicular to from this seal, across the skirt, to the edge of the article. The length of a skirt terminates in the “ends” of the skirt or header.

The top seal is made after the product is placed in the packaging article. As used herein, the phrase “skirt” refers to that portion of the packaging article that is outward of a heat seal, e.g., the excess length or width on the non-product side of any factory heat seal on the packaging article. In an end-seal bag, the bag skirt is short in the machine direction and long in the transverse direction. In a side-seal bag, the bag skirt is long in the machine direction and short in the transverse direction. In either case, the “width” of the bag skirt is the shorter dimension of the skirt, and the “length” of the bag skirt is the longer dimension of the skirt. A bag skirt (or any skirt of any packaging article) can have a width, before the film is shrunk, of at least 5 millimeters, or at least 10 millimeters, or at least 15 millimeters, or at least 20 millimeters, or at least 25 millimeters, or at least 30 millimeters. Alternatively, the skirt can have a width of from 5 to 100 millimeters, or from 10 to 50 millimeters, or from 15 to 40 millimeters, or from 20 to 35 millimeters.

As used herein, the phrase “lay-flat bag” refers generically to non-gusseted bags used for the packaging of a variety of products, particularly food products. More specifically, the phrase “lay-flat bag” includes side seal bag, end-seal bag, L-seal bag, U-seal bag (also referred to as a pouch), and backseamed bag (also referred to as T-seal bag). The backseam can be a fin seal, a lap seal, or a butt-seal with a backseaming tape. Before the bag is shrunk, it can have a length-to-width ratio of from 1:1 to 20:1; or from 1.5:1 to 8:1; or from 1.8:1 to 6:1; or from 2:1 to 4:1. The bag can have a length of from 6 inches to 60 inches, or 10 inches to 48 inches, or 12 inches to 40 inches, or 15 inches to 36 inches.

As used herein, the terms “seal” and “sealed” refer broadly to various different means of (i) affixing two portions of a film surface together (e.g., end seal, fin seal, etc), or (ii) affixing two portions of two different surfaces of the same film together (e.g., lap seal), or (iii) affixing portions of surfaces of different films together (e.g., the seals in a pouch). Moreover, the term “sealed” is inclusive of diverse ways of affixing film portions together, e.g., heat sealing, adhering with adhesive, adhering with corona treatment, etc.

The phrases “seal layer,” “sealing layer,” “heat seal layer,” and “sealant layer,” refer to an outer film layer, or layers, involved in heat sealing the film to itself, another film layer of the same or another film, and/or another article which is not a film. Heat sealing can be performed in any one or more of a wide variety of manners, such as melt-bead sealing, thermal sealing, impulse sealing, ultrasonic sealing, hot air sealing, hot wire sealing, infrared radiation sealing, ultraviolet radiation sealing, electron beam sealing, etc. A heat seal is usually a relatively narrow seal (e.g., 0.02 inch to 1 inch wide) across a film. One particular heat sealing means is a heat seal made using an impulse sealer, which uses a combination of heat and pressure to form the seal, with the heating means providing a brief pulse of heat while pressure is being applied to the film by a seal bar or seal wire, followed by rapid cooling.

In some embodiments, the seal layer can comprise a polyolefin, particularly an ethylene/alpha-olefin copolymer and/or an ionomer resin. For example, the seal layer can contain a polyolefin having a density of from 0.88 g/ec to 0.917 glee, or from 0.90 glee to 0.917 g/cc. More particularly, the seal layer can comprise at least one member selected from the group consisting of very low density polyethylene and homogeneous ethylene/alpha-olefin copolymer. Very low density polyethylene is a species of heterogeneous ethylene/alpha-olefin copolymer. The heterogeneous ethylene/alpha-olefin (e.g., very low density polyethylene) can have a density of from 0.900 to 0.917 g/cm³. The homogeneous ethylene/alpha-olefin copolymer in the seal layer can have a density of from 0.880 g/cm³ to 0.910 g/cm³, or from 0.880 g/cm³ to 0.917 g/cm³. Homogeneous ethylene/alpha-olefin copolymers useful in the seal layer include metallocene-catalyzed ethylene/alpha-olefin copolymers having a density of from 0.917 g/cm³ or less, as well as a very low density polyethylene having a density of 0.912 g/cm³, these polymers providing excellent optics. Plastomer-type metallocene sealants with densities less than 0.910 g/cm³ also provided excellent optics.

As used herein, the term “barrier”, and the phrase “barrier layer”, as applied to films and/or film layers, are used with reference to the ability of a film or film layer to serve as a barrier to one or more gases. The film used to make the packaging receptacle can optionally comprise a barrier layer. In the packaging art, oxygen (i.e., gaseous O₂) barrier layers can comprise, for example, at least one member selected from the group consisting of hydrolyzed ethylene/vinyl acetate copolymer (designated by the abbreviations “EVOH” and “HEVA”, and also referred to as “saponified ethylene/vinyl acetate copolymer” and “ethylene/vinyl alcohol copolymer”), polyvinylidene chloride, amorphous polyamide, polyamide MXD6 (particularly MXD6/MXDI copolymer), polyester, polyacrylonitrile, etc., as known to those of skill in the art. In addition to the first and second layers, the film may further comprise at least one barrier layer.

The film can exhibit O₂-transmission rate of from 1 to 20 ce/m² day atm at 23° C. and 100% relative humidity, or from 2 to 15 cc/m² day atm at 23° C. and 100% relative humidity, or from 3 to 12 cc/m² day atm at 23° C. and 100% relative humidity, or from 4 to 10 cc/m² day atm at 23° C. and 100% relative humidity. Alternatively, the film can exhibit an O₂-transmission rate of from 21 cc/m² day atm to 15,000 cc/m² day atm, or from 500 cc/m² day atm to 10,000 cc/m² day atm, or from 2000 cc/m² day atm to 6,000 cc/m² day atm. O₂-transmission rate can be measured in accordance with ASTM-D-3985.

As used herein, the phrase “tie layer” refers to any internal layer having the primary purpose of adhering two layers to one another. Tie layers can comprise any polymer having a polar group grafted thereon. Such polymers adhere to both nonpolar polymers such as polyolefin, as well as polar polymers such as polyamide and ethylene/vinyl alcohol copolymer. Tie layers can comprise at least one member selected from the group consisting of polyolefin (particularly homogeneous ethylene/alpha-olefin copolymer), anhydride-modified polyolefin, ethylene/vinyl acetate copolymer, and anhydride-modified ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer, and ethylene/methyl acrylate copolymer. Typical tie layer polymers comprise at least one member selected from the group consisting of anhydride modified linear low density polyethylene, anhydride modified low density polyethylene, anhydride modified polypropylene, anhydride modified methyl acrylate copolymer, anhydride modified butyl acrylate copolymer, homogeneous ethylene/alpha-olefin copolymer, and anhydride modified ethylene/vinyl acetate copolymer.

As used herein, the phrases “inner layer” and “internal layer” refer to any layer, of a multilayer film, having both of its principal surfaces directly adhered to another layer of the film.

As used herein, the phrase “outer layer” refers to any film layer having less than two of its principal surfaces directly adhered to another layer of the film. A multilayer film has two outer layers, each of which has a principal surface adhered to only one other layer of the multilayer film.

As used herein, the term “adhered” is inclusive of films which are directly adhered to one another using a heat seal or other means, as well as films which are adhered to one another using an adhesive which is between the two films. This term is also inclusive of layers of a multilayer film, which layers are of course adhered to one another without an adhesive therebetween. The various layers of a multilayer film can be “directly adhered” to one another (i.e., no layers therebetween) or “indirectly adhered” to one another (i.e., one or more layers therebetween).

Once a multilayer film is heat sealed to itself or another member of the package being produced (i.e., is converted into a packaging article, e.g., a bag, pouch, or casing), one outer layer of the film is an inside layer of the packaging article and the other outer layer becomes the outside layer of the packaging article. The inside layer can be referred to as an “inside heat seal/product contact layer”, because this is the film layer that is sealed to itself or another article, and it is the film layer closest to the product, relative to the other layers of the film. The other outer layer can be referred to as the “outside layer” and/or as the “outer abuse layer” or “outer skin layer”, as it is the film layer furthest from the product, relative to the other layers of the multilayer film. Likewise, the “outside surface” of a packaging article (i.e., bag) is the surface away from the product being packaged within the article.

While the film can be sealed to itself to form a packaging article, optionally a patch film can be adhered to the packaging receptacle. The patch film can be heat-shrinkable or non-heat-shrinkable. The patch may or may not cover a heat seal. If the patch covers a heat seal, optionally the heat seal may be made through the patch. If the tear is to be made though the bag and through the patch, the patch should cover a heat seal, and the tear initiator should be through both the bag film and the patch film. The bag can have a curved seal and the patch can extend into and through the region of the curved seal and over and past the curved seal. If the bottom edge of the bag is curved, a bottom edge of the patch can also be curved. The patch bag can have any desired configuration of patch on bag as disclosed in any one or more of U.S. Pat. Nos. 4,755,403, 5,540,646, 5,545,419, 6,296,886, 6,383,537, 6,663,905, and 6,790,468, each of which is hereby incorporated, in its entirety, by reference thereto.

End-seal bags with curved heat seals, and end-seal patch bags with curved heat seals, can be designed for have manual tear initiation and manual directional tear propagation. While the end-seal may be curved, the bottom edge of the bag may be straight across the tubing, or may also be curved. A curved bottom heat seal and a straight across bag bottom edge leaves more space in the bottom corners of the bag skirt for providing tear initiators, as well as for grip assisters. Patch bags with curved end seals are disclosed in U.S. Pat. No. 6,270,819, to Wiese, which is hereby incorporated, in its entirety, by reference thereto.

The term “polymer”, as used herein, is inclusive of homopolymer, copolymer, terpolymer, etc. “Copolymer” includes copolymer, terpolymer, etc.

The tear initiation, tear propagation, and linear tear property of a monolayer or multilayer film may also be enhanced by providing the film with a filler material, such as an inorganic filler. Polymeric systems that incorporate high filler concentrations may also enhance linear tear behavior. Depending on the particle size and dispersion, a filler concentration as low as 5 weight percent filler (i.e., based on total layer weight) in ethylene/alpha-olefin copolymer, polypropylene, propylene/ethylene copolymer, polybutylene, polystyrene/butadiene copolymer, ionomer resin, ethylene/vinyl acetate copolymer, ethylene/butyl acrylate copolymer, ethylene/methyl acrylate copolymer, ethylene/acrylic acid copolymer, polyester, polyamide, etc., may contribute to the linear tear behavior. More particularly, the presence of filler in an amount of from 5 to 95 weight percent, or in an amount of from 5 to 50 weight percent, or in an amount of from 10 to 40 weight percent, or from 20 to 35 weight percent, may be used.

Suitable fillers include silicates (particularly sodium silicate, potassium silicate, and aluminum silicate, alkali alumino silicate), silica (particularly amorphous silica), siloxane, silicone resin, zinc sulfide, wollastonite, microspheres, glass fiber, metal oxide (particularly oxides of titanium, zinc, antimony, magnesium, iron, and aluminum), calcium carbonate, sulfate (particularly barium sulfate and calcium sulfate), aluminum trihydrate, feldspar, perlite, gypsum, iron, fluoropolymer, crosslinked polymethylmethacrylate, talc, diatomaceous earth, zeolites, mica, kaolin, carbon black, and graphite.

The filler concentration required to achieve low tear initiation force is dependent on particle geometry, particle size, particle aspect ratio, and compatibility of the filler and the polymer matrix. Some fillers are chemically treated to improve the compatibility of the particle and the polymer into which it is dispersed.

As used herein, terms such as “polyamide”, “polyolefin”, “polyester”, etc are inclusive of homopolymers of the genus, copolymers of the genus, terpolymers of the genus, etc, as well as graft polymers of the genus and substituted polymers of the genus (e.g., polymers of the genus having substituent groups thereon).

The phrase “ethylene/alpha-olefin copolymer” is particularly directed to heterogeneous copolymers such as linear low density polyethylene (LLDPE), very low and ultra low density polyethylene (VLDPE and ULDPE), as well as homogeneous polymers such as metallocene catalyzed polymers such as EXACT° resins obtainable from the Exxon Chemical Company, and TAFMER® resins obtainable from the Mitsui Petrochemical Corporation. All these latter copolymers include copolymers of ethylene with one or more comonomers selected from C₄ to C₁₀ alpha-olefin such as butene-1 (i.e., 1-butene), hexene-1, octene-1, etc. in which the molecules of the copolymers comprise long chains with relatively few side chain branches or cross-linked structures. This molecular structure is to be contrasted with conventional low or medium density polyethylenes which are more highly branched than their respective counterparts. The heterogeneous ethylene/alpha-olefins commonly known as LLDPE have a density usually in the range of from about 0.91 grams per cubic centimeter to about 0.94 grams per cubic centimeter. Other ethylene/alpha-olefin copolymers, such as the long chain branched homogeneous ethylene/alpha-olefin copolymers available from the Dow Chemical Company, known as AFFINITY® resins, are also included as another type of homogeneous ethylene/alpha-olefin copolymer useful in the film and process described herein.

As used herein, the phrase “heterogeneous polymer” refers to polymerization reaction products of relatively wide variation in molecular weight and relatively wide variation in composition distribution, i.e., typical polymers prepared, for example, using conventional Ziegler-Natta catalysts. Heterogeneous copolymers typically contain a relatively wide variety of chain lengths and comonomer percentages. Heterogeneous copolymers have a molecular weight distribution (Mw/Mn) of greater than 3.0.

As used herein, the phrase “homogeneous polymer” refers to polymerization reaction products of relatively narrow molecular weight distribution and relatively narrow composition distribution. Homogeneous polymers are useful in various layers of multilayer films. Homogeneous polymers are structurally different from heterogeneous polymers, in that homogeneous polymers exhibit a relatively even sequencing of comonomers within a chain, a mirroring of sequence distribution in all chains, and a similarity of length of all chains, i.e., a narrower molecular weight distribution. Furthermore, homogeneous polymers are typically prepared using metallocene, or other single-site type catalysis, rather than using Ziegler Natta catalysts. Homogeneous ethylene/alpha-olefin copolymer can have a Mw/Mn of <3.0.

As used herein, the term “polyamide” refers to a polymer having amide linkages, more specifically synthetic polyamides, either aliphatic or aromatic, either in semi-crystalline or amorphous form. It is intended to refer to both polyamides and co-polyamides. The polyamides can be selected from nylon compounds approved for use in producing articles intended for use in processing, handling, and packaging food, including homopolymers, copolymers and mixtures of the nylon materials described in 21 C.F.R. 177.1500 et seq., which is incorporated herein by reference. Exemplary of such polyamides include nylon homopolymers and copolymers such as those selected from the group consisting of nylon 4,6 (poly(tetramethylene adipamide)), nylon 6 (polycaprolactam), nylon 6,6 (poly(hexamethylene adipamide)), nylon 6,9 (poly(hexamethylene nonanediamide)), nylon 6,10 (poly(hexamethylene sebacamide)), nylon 6,12 (poly(hexamethylene dodecanediamide)), nylon 6/12 (poly(caprolactam-co-laurallactam)), nylon 6,6/6 (poly(hexamethylene adipamide-co-caprolactam)), nylon 6/66 (poly(caprolactam-co-hexamethylene adipamide)), nylon 66/610 (e.g., manufactured by the condensation of mixtures of nylon 66 salts and nylon 610 salts), nylon 6/69 resins (e.g., manufactured by the condensation of epsilon-caprolactam, hexamethylenediamine and azelaic acid), nylon 11 (polyundecanolactam), nylon 12 (polyauryllactam), nylon MXD6, nylon MXDI, nylon 61/6T, and copolymers or mixtures thereof. Unless otherwise indicated, the phrase “semi-crystalline polyamide” includes all polyamides that are not considered to be amorphous polyamides. All semi-crystalline polyamides have a determinable melting point.

In one embodiment, the film does not comprise a crosslinked polymer network. In another embodiment, the film comprises a crosslinked polymer network. Optionally, the film can be irradiated to induce crosslinking of polymer, particularly polyolefin in the film. The film can be subjected to irradiation using an energetic radiation treatment, such as corona discharge, plasma, flame, ultraviolet, X-ray, gamma ray, beta ray, and high energy electron treatment, which induce cross-linking between molecules of the irradiated material. The irradiation of polymeric films is disclosed in U.S. Pat. No. 4,064,296, to BORNSTEIN, et. al., which is hereby incorporated in its entirety, by reference thereto. BORNSTEIN, et. al. discloses the use of ionizing radiation for crosslinking polymer present in the film.

Radiation dosages are referred to herein in terms of the radiation unit “RAD”, with one million RADS, also known as a megarad, being designated as “MR”, or, in terms of the radiation unit kiloGray (kGy), with 10 kiloGray representing I MR, as is known to those of skill in the art. A suitable radiation dosage of high energy electrons is in the range of up to about 16 to 166 kGy, more preferably about 30 to 90 kGy, and still more preferably, 30 to 50 kGy. Preferably, irradiation is carried out by an electron accelerator and the dosage level is determined by standard dosimetry processes. Other accelerators such as a van der Graaf or resonating transformer may be used. The radiation is not limited to electrons from an accelerator since any ionizing radiation may be used.

As used herein, a film that curls away from the tear line when torn is exemplified by a film that curls in a direction perpendicular to the tear line. For example, FIG. 1D illustrates a packaging article that has been torn, with the film curling directly away from the tear line, in a direction that appears to be perpendicular to the tear line. Moreover, in FIG. 1D, the torn film is also curling “outward” in that the film curls toward the outside surface of the packaging article, rather than towards the inside surface of the packaging article. In so doing, the “outward” surface of the curled portion of the film is the surface that formed the inside of the package before the film was torn. As a result, if a sterile nurse inadvertently contacts the outside of the curled portion of the film, contamination does not occur because the outside surface of the curled portion of the film is sterile from the sterilization process and has not contacted any other surface prior to the package being torn open.

As used herein, the packaging article is disclosed as having been “made from” a flexible film. This means that the packaging article comprises a flexible film, i.e., includes the flexible film, but can include further components that are not flexible films. As used herein, the phrase “an article . . . being made from X . . . ” refers to an article that contains at least X but is free to contain further components than X.

The phrase “lay-flat side” is used herein with reference to those discrete portions a packaging article which lay flat when the packaging article is empty and placed on a flat surface it its most flat configuration without stretching or distorting the article. An end seal bag has two lay-flat sides, as does a side-seal bag and a U-sealed pouch. Each lay-flat side of an end-seal bag is bounded by the top edge, the fold at each of the two side edges, and the bottom edge. Similarly, each lay-flat side of a side-seal bag is bounded by the top edge, the fold at the bottom edge, the first side edge, and the second side edge.

As used herein with respect to the contents inside a packaging article, the term “product” includes both a single product article as well as multiple product articles. Multiple product articles can be a multiple of identical product articles, multiple product articles each of which is different from the others, as well as multiple product articles in including, within the same package, at least two identical product articles and at least two different product articles having at least one different feature.

Viewing FIG. 1A and FIG. 1B together, preferred end-seal packaging receptacle 20 is made from seamless film tubing 22 that has an open top defined by top edge 26, a bottom edge 28, folded first side edge 30, and folded second side edge 32. The front side of receptacle 20 is herein referred to as the first lay-flat side, and the rear side of receptacle 20 is herein referred to as the second lay-flat side of receptacle 20. End-seal 34 is a heat seal of the first lay flat side to the second lay-flat side. End seal 34 extends transverse to the length of seamless film tubing 22. End seal 34 runs the full width of packaging receptacle 20, i.e., from folded first side edge 30 to folded second side edge 32.

Between end seal 34 and bottom edge 28 is skirt 36, with the first lay-flat side of skirt 36 containing first tear initiator 38, which is a first slit in the skirt and is oriented in the lengthwise direction of the tubing, i.e., the so-called “machine direction”, which is the direction in which the film was extruded. The second lay-flat side of skirt 36 contains second tear initiator 39. When in the lay-flat configuration, first tear initiator 38 is positioned directly over top of second tear initiator 39. The first lay-flat side of skirt 36 also contains first grip-assister 40 and second grip assister 42, each of which is a curved slit through film 22. FIG. 1B illustrates first and second grip assisters 40 and 42, with the respective curved slits through film 22 producing hanging chads 41 and 43, respectively, inside curved slits 40 and 42, respectively.

As can be understood from FIG. 1B, after converting packaging receptacle 20 to a packaging article, the manual tearing is preferably carried out in a manner that initiates and propagates tears from both first tear initiator 38 on the first lay-flat side, as well as from the second tear initiator 39 on the second lay-flat side.

FIG. 1C illustrates an enlarged perspective view of a vented portion of the packaging receptacle 20 of FIGS. 1A and 1B. As is apparent in FIG. 1C, each vent hole is defined by edge 44 of film 22. The hole inside of each film edge 44, and a region of the outside surface of the film 22, i.e., the outside surface of a region of the film outward of and around each film edge 44, is covered by semipermeable membrane 46, which also extends over the entire hole inside edge 44 of film 22. Film 22 is heat welded to each discrete piece of semipermeable membrane 46 in regions 50 outward of hole edges 44 but inward of semipermeable membrane edges 48.

FIG. 1D is a perspective view of a packaged product 52 made utilizing the packaging receptacle of FIGS. 1A, 1B, and 1C. Packaged product was prepared by providing a packaging receptacle 20 as per FIG. 1, placing a medical product 54 (as illustrated, a blanket) inside packaging receptacle 20, and thereafter sealing packaging receptacle 20 closed, resulting in packaging article 56 as illustrated in FIG. 1D. After subjecting the resulting packaged product 52 to a sterilization procedure (e.g., exposure to ethylene oxide gas permeating into package through semipermeable membranes 46 to sterilize product 54), packaged product 52 is taken to a point of use and opened by manually-initiating and manually-propagating tears through both lay-flat sides of the skirt, i.e., skirt 36, with the first and tears being initiated and propagated from tear initiators 38 and 39, respectively. The initiation and propagation of a tear down the length of the first side of packaging article 56 results in first torn edge 58 and second torn edge 60, both of which tears are through a region of the first lay-flat side of the end-seal bag that was sealed closed by top seal 57 below top edge 26 to produce packaging article 56. The manually-initiated tearing produces a second tear defined by third torn edge 59 and fourth torn edge 61 on second lay-flat side of packaging article 56. As is apparent in FIG. 1D, film 22 on first lay-flat side of packaging article 56 curls away from product 54 along first and second torn edges 58 and 60. Similar curling away from product 54 is exhibited by third and fourth torn edges 59 and 61. This curling away from the product lowers the likelihood that either product 54, or a sterile nurse removing product 54 from packaging article 56, will contact a potentially non-sterile outside surface of packaging article 56 as packaging article 56 is torn and as product 54 is removed from packaging article 56. The first and second tears can be manually-propagated through to edge 26 so that packaging article 56 is separated into halves, thereby exposing a large portion of product 54 for the sterile nurse to grab and remove from the remainder of packaging article 254.

FIG. 1E is a perspective view of comparative packaged product 62 in the process of being torn open, with product 54 inside of comparative packaging article 64. Comparative packaging article 64 is identical to packaging article 56 of FIG. 1D, with the exception that film 23 from which comparative packaging article 64 was a film lacking curl when torn. Thus, as comparative packaging article 64 was torn open, film along first and second torn edges 66 and 68 does not curl away from product 54. The result is that there is a higher likelihood that product 54, or a sterile nurse removing product 54, will contact the potentially non-sterile outside surface of comparative packaging article 64 as comparative packaging article 64 is torn open by a non-sterile nurse and product 54 is removed from comparative packaging article 64 by the sterile nurse.

FIG. 2 is a schematic illustration of a first embodiment of a preferred side-seal packaging receptacle 70 in accordance with the invention. Side-seal packaging receptacle 70 can be made from a seamless film tubing that has been extruded from an annular die and slit along the length of the tubing, or made by folding a flat film extruded from a slot die. Side-seal packaging receptacle 70 has an open top defined by top edge 72, a folded bottom edge 74, first side edge 76, first side seal 78, first skirt 80, second side edge 82, second side seal 84, and second skirt 86. The front side of side-seal packaging receptacle 70 is herein referred to as the first lay-flat side, and the rear side of receptacle 70 is herein referred to as the second lay-flat side of receptacle 70. First side-seal 78 is a heat seal of the first lay-flat side to the second lay-flat side, and second side-seal 84 is also a heat seal of the first lay-flat side to the second lay-flat side. First and second side seals 78 and 84 extend the full length of side-seal packaging receptacle 70, i.e., from folded bottom edge 74 to the open top edge 72.

Along top edge 72 are first tear initiator 88 in first lay-flat side of packaging receptacle 70, and second tear initiator 90 in second lay-flat side of packaging receptacle 70. After a product is placed inside of packaging receptacle 70, packaging receptacle is closed by making a closing seal (not shown) across the width of receptacle 70, this closing seal being of the first lay-flat side to the second lay-flat side. This closing seal is made above the product inside of packaging receptacle 70, but below the ends of tear initiators 88 and 90. The result is a packaging article having a skirt between the closing seal and top edge 72. When in the lay-flat configuration, first tear initiator 88 is positioned directly over top of second tear initiator 90.

A first grip assister slit 92 is provided on one side of tear initiator 88, and a second grip-assister slit 94 is provided on the other side of tear initiator 88. While grip assisters 92 and 94 are shown only on first lay-flat side of packaging receptacle 70, the second lay-flat side of packaging receptacle is preferably provided with corresponding tear initiators, and preferably the grip assisters on the second lay-flat side are coincident with grip assisters 92 and 94 on the first lay-flat side of side-seal packaging receptacle 70.

Packaging receptacle 70 is also provided with four vents in the form of four holes through the first lay-flat side of the film. The holes are defined by film edges 96. The holes are covered by a semipermeable membrane having edges 98. The first lay-flat side of the film is bonded to the semipermeable membrane in overlap area 100.

Instead of being along the top edge of packaging receptacle 70, tear initiators 88 and 90 could be placed, for example, in the first and second lay-flat sides of first skirt 80. The tear initiators would be positioned for the initiation and propagation of a transverse tear across packaging receptacle 70. This tear could be across packaging receptacle 70 at a location between the vents, or along bottom edge 74, or along the closing seal described above.

FIG. 3 is a schematic of alternative side-seal packaging receptacle 102 in accordance with the invention. As with side-seal packaging receptacle 70, side-seal packaging receptacle 102 can be made from tubular film extruded from an annular die and thereafter slit lengthwise to make a folded film or to make a flat film that is thereafter folded, or made from a flat film extruded from a slot die and thereafter folded. Side-seal packaging receptacle 102 has an open top defined by top edge 104, a folded bottom edge 106, first side edge 108, first side seal 110, first skirt 112, second side edge 114, second side seal 116, and second skirt 118. The front side of packaging receptacle 102 is herein referred to as the first lay-flat side, and the rear side of packaging receptacle 102 is herein referred to as the second lay-flat side of packaging receptacle 102. First side-seal 110 is a heat seal of the first lay-flat side to the second lay-flat side, and second side-seal 116 is also a heat seal of the first lay-flat side to the second lay-flat side. First and second side seals 110 and 116 extend the full width of side-seal packaging receptacle 102, i.e., from folded bottom edge 106 to the open top edge 104.

In second skirt 118 is first tear initiator slit 120 in first lay-flat side of packaging receptacle 102. A second tear initiator (not illustrated) is in a corresponding position on the second lay-flat side of second skirt 118, so that first tear initiator slit 120 lies directly over the second tear initiator (not illustrated) when packaging receptacle 102 is in its lay-flat configuration. After a product is placed inside of packaging receptacle 102, packaging receptacle is closed by making a closing seal (not shown) down the length of packaging receptacle 102, the seal being of the first lay-flat side to the second lay-flat side. This closing seal is made above the product but at or below top edge 104.

A first grip assister slit 122 is provided on one side of tear initiator 120, and a second grip-assister slit 124 is provided on the other side of tear initiator 120. While grip assisters 122 and 124 are shown only on first lay-flat side of packaging receptacle 102, the second lay-flat side of packaging receptacle is preferably provided with corresponding tear initiators (not illustrated in FIG. 3).

Packaging receptacle 102 is also provided with four vents in the form of four holes through the first lay-flat side of the film from which packaging article 102 is made. The holes are defined by film edges 126. The holes are covered by a semipermeable membrane having edges 128. The outside surface of the first lay-flat side of the film is bonded to the semipermeable membrane in overlap area 130.

FIG. 4 is a schematic of L-seal packaging receptacle 132 in accordance with the invention. L-seal packaging receptacle 132 can be made from a film extruded from an annular die as a tubing that is thereafter slit to provide a flat film that is already folded or is later folded, or made from a film extruded from a slot die as a flat film that is thereafter folded to make packaging receptacle 132. L-seal packaging receptacle 132 has an open top defined by top edge 134, folded first side edge 136, second side edge 138, bottom edge 140, bottom seal 142, side seal 144, side skirt 146, and bottom skirt 150. The front side of packaging receptacle 132 is herein referred to as the first lay-flat side, and the rear side of packaging receptacle 132 is herein referred to as the second lay-flat side of packaging receptacle 132. Side-seal 144 is a heat seal of the first lay-flat side to the second lay-flat side, and bottom-seal 142 is also a heat seal of the first lay-flat side to the second lay-flat side. Side seal 144 extends the full length of packaging receptacle 132, i.e., from bottom edge 140 to top edge 134. Bottom seal 142 extends the full width of packaging receptacle 132, i.e., from folded first side edge 136 to second side edge 138.

In bottom skirt 150 is first tear initiator 152 in first lay-flat side of packaging receptacle 132, and second tear initiator 154 in second lay-flat side of packaging receptacle 132. Second tear initiator 1.54 is in a position on the second lay-flat side of bottom skirt 150, so that first tear initiator 152 lies directly over the second tear initiator 154 when packaging receptacle 132 is in its lay-flat configuration. After a product is placed inside of packaging receptacle 132, packaging receptacle 132 is closed by making a closing seal (not shown) across the width of packaging receptacle 132, the seal being of the first lay-flat side to the second lay-flat side. This closing seal is made above the product but at or below top edge 134.

A first grip assister slit 156 is provided on one side of tear initiator 152, and a second grip-assister slit 158 is provided on the other side of tear initiator 152. While grip assisters 156 and 158 are shown only on first lay-flat side of packaging receptacle 132, the second lay-flat side of packaging receptacle 132 is preferably provided with corresponding tear initiators (not illustrated in FIG. 4).

Packaging receptacle 132 is also provided with four vents in the form of four holes through the first lay-flat side of the film. The holes are defined by film edges 160. The holes are covered by a semipermeable membrane having edges 162. The outside surface of the first lay-flat side of the film is bonded to the semipermeable membrane in overlap area 164.

FIG. 5 is a schematic of a first embodiment of a pouch-type packaging receptacle 166 in accordance with the invention. Pouch-type packaging receptacle 166 is made from two separate pieces of film. The two pieces of film can be identical or different with respect to the number of film layers (they could be monolayer or multilayer) and with respect to the composition of the layer(s). The film can be extruded from an annular die as a tubing that is thereafter slit lengthwise to provide a flat film that is then cut transversely to produce two pieces of film, or can be made from a film extruded from a slot die as a flat film that is thereafter cut into two pieces to make pouch-type packaging receptacle 166. Pouch-type packaging receptacle 166 has an open top defined by top edge 168, first side edge 170, first side seal 172, first side skirt 174, second side edge 176, second side seal 178, second side skirt 180, bottom edge 182, bottom seal 184, bottom skirt 186. The front side of packaging receptacle 166 is herein referred to as the first lay-flat side, and the rear side of packaging receptacle 166 is herein referred to as the second lay-flat side of packaging receptacle 166. First and second side-seals 172 and 178, and bottom seal 184, are all heat seals of the first lay-flat side to the second lay-flat side. Side seals 172 and 178 extend the full length of packaging receptacle 166, i.e., from bottom edge 182 to top edge 168. Bottom seal 184 extends the full width of packaging receptacle 166, i.e., from first side edge 170 to second side edge 176.

In bottom skirt 186 is first tear initiator 188 in first lay-flat side of packaging receptacle 166, and second tear initiator 190 in second lay-flat side of packaging receptacle 166. Second tear initiator 190 is in a position on the second lay-flat side of bottom skirt 186, so that first tear initiator 188 lies directly over the second tear initiator 190 when packaging receptacle 166 is in its lay-flat configuration. After a product is placed inside of packaging receptacle 166, packaging receptacle 166 is closed by making a closing seal (not shown) across the width of packaging receptacle 166, the seal being of the first lay-flat side to the second lay-flat side. This closing seal is made above the product but at or below top edge 168.

A first grip assister slit 192 is provided on one side of tear initiator 188, and a second grip-assister slit 194 is provided on the other side of tear initiator 188. While grip assisters 192 and 194 are shown only on first lay-flat side of packaging receptacle 166, the second lay-flat side of packaging receptacle 166 is preferably provided with corresponding tear initiators (not illustrated in FIG. 5).

Packaging receptacle 166 is also provided with four vents in the form of four holes through the first lay-flat side of the film. The holes are defined by film edges 196. The holes are covered by a semipermeable membrane having edges 198. The outside surface of the first lay-flat side of the film is bonded to the semipermeable membrane in overlap area 200.

FIG. 6 is a schematic of an alternative pouch-type packaging article 202 in accordance with the invention. As illustrated in FIG. 6, pouch-type packaging article 202 has been sealed closed for purposes of illustration and description only, as it has no product inside but in actual use would have a product inside when sealed closed. Pouch-type packaging article 202 is made from two separate pieces of film. The two pieces of film can be identical or different with respect to the number of film layers (they could be monolayer or multilayer) and with respect to the composition of the layer(s). The film(s) can be extruded from an annular die as a tubing that is thereafter slit lengthwise to provide a flat film that is then cut transversely to produce one or more pieces of film, or can be made from a film extruded from a slot die as a flat film that is thereafter cut into one or more pieces of film.

Pouch-type packaging article 202 has top edge 204, top seal 206, top skirt 208, first side edge 210, first side seal 212, first side skirt 214, second side edge 216, second side seal 218, second side skirt 220, bottom edge 222, bottom seal 224, and bottom skirt 226. The front side of packaging article 202 is herein referred to as the first lay-flat side, and the rear side of packaging article 202 is herein referred to as the second lay-flat side of packaging article 202. First and second side-seals 212 and 218, and bottom seal 224, are all heat seals of the first lay-flat side to the second lay-flat side. Side seals 212 and 218 extend the full length of packaging receptacle 202, i.e., from bottom edge 222 to top edge 204. Bottom seal 224 extends the full width of packaging article 202, i.e., from first side edge 210 to second side edge 216.

In the first lay-flat side of packaging article 202, first tear initiator 228 is in bottom skirt 226. In the second lay-flat side of packaging article 202, second tear initiator 230 is in bottom skirt 226. Second tear initiator 230 is in a position so that first tear initiator 228 lies directly over the second tear initiator 230 when packaging article 202 is in its lay-flat configuration. Also in the first lay-flat side of packaging article 202, third tear initiator 232 is in the first lay-flat side of first side skirt 214. In the second lay-flat side of packaging article 202, fourth tear initiator (not illustrated in FIG. 6) is also present in first side skirt 214. The fourth tear initiator is in a position so that third tear initiator 232 lies directly over the fourth tear initiator (again, not illustrated) when packaging article 202 is in its lay-flat configuration.

Due to the location of the first, second, third, and fourth tear initiators near the corners of packaging article 202, grip assisters are not provided in the embodiment of FIG. 6. However, providing grip assisters on one or both sides of tear initiators 228, 230, 232, and the fourth grip assister under third grip assister 232.

Packaging article 202 is also provided with four vents in the form of four holes through the first lay-flat side thereof. The holes are defined by film edges 234. The holes are covered by a semipermeable membrane having edges 236. The outside surface of the first lay-flat side of the film is bonded to the semipermeable membrane in overlap area 238.

The packaging article of FIG. 6 provides an advantage over a packaging article made from the packaging receptacle of FIG. 5. The advantage is that the packaging article of FIG. 6 allows two intersecting tears to be made with the result that a free corner of film is available to curl up and expose a product inside the package. More particularly, first and second lengthwise tears (i.e., tears running the length of the packaging article, with the lengthwise tears being though both lay-flat sides) is made up the length of packaging article 202 along a tear lines initiated from first and second tear initiators 228 and 230. The first and second tears are propagated along a tear line parallel to second side seal 218, with the first and second tears being propagated the full length of packaging article, or up to top seal 206. Thereafter, third and fourth transverse tears (i.e., tears running the width of the packaging article, with the transverse tears being through both lay-flat sides) are made across the width of packaging article 202, along tear lines initiated from third initiator 232 and fourth tear initiator (described above, but not illustrated). The third and fourth tears are propagated parallel to top seal 206, with the third and fourth tears being propagated across the packaging article until they intersect the first and second lengthwise tears, respectively. Once the third and fourth tears intersect the first and second tears, film corner 240 of the first lay-flat side, and a corresponding film corner of the second lay-flat side, are free to curl back toward dashed line 242, away from the product inside the packaging article being opened. The result is exposure of the sterile product inside the packaging article, for ease of transfer to a sterile nurse.

FIG. 7 illustrates a schematic view of an alternative packaging receptacle in the form of an end-seal bag 244, which has been made from seamless tubing of film 246. End-seal bag 244 has an open top defined by top edge 248, a bottom edge 250, folded first side edge 252, and folded second side edge 254. The front side of end-seal bag 244 is herein referred to as the first lay-flat side of end-seal bag 244, and the rear side of end-seal bag 244 is herein referred to as the second lay-flat side of end-seal bag 244. End-seal 256 is a heat seal of the first lay flat side to the second lay-flat side. End seal 256 extends transverse to the length of seamless film tubing 22, and is a heat seal of the inside surface of film tubing 246 to itself. End seal 256 runs the full width of end-seal bag 244, i.e., from folded first side edge 252 to folded second side edge 254.

Between end seal 256 and bottom edge 250 is skirt 258, with the first lay-flat side of skirt 258 containing first tear initiator 260, which is a first slit in the skirt and is oriented in the lengthwise direction of the tubing. The second lay-flat side of skirt 36 contains second tear initiator 262. First and second tear initiators 260 and 262 are located close and parallel to first side edge 252, so that after a product is placed inside end-seal bag 244 and a top seal is made across bag 244 to produce a packaged product in which the product is surrounded by the packaging article, first and second manually-initiated, manually-propagated tears from respective first and second tear initiators 260 and 262 will propagate parallel to first side edge 252, all the way to top edge 248, resulting in a relatively narrow strip of film being separated from the remainder of the packaging article. This allows an opening of the packaging article up its full length, with an outside surface of the removed strip of film having little opportunity to contact the sterile product within the remainder of the packaging article, as little if any of the product is likely to be in the vicinity of the first and second tears. The curling back of the film from the product provides a sterile inside surface in the event of contact with the bag during the removal of the product by a sterile nurse. As illustrated in FIG. 7, end-seal bag is provided with a plurality of vent holes defined by film edges 264, with each vent hole being covered by semipermeable membrane 266, with the semipermeable membranes being bonded to film 246 in overlapping region 268.

FIG. 8 is a schematic of a comparative packaged product 270 in which product 283 is surrounded by a prior art packaging article. The packaging article comprises lay-flat pouch 272 made from a front film piece and a back film piece, and spunbonded fibrous header strip 280. The front and back film pieces are heat sealed to one another across bottom edge 274, a lower portion of first side edge 276, and a lower portion of second side edge 278. Although the front and back film pieces have the same width, the front film piece has a top edge which is bonded to a bottom edge of header strip 280 at seal 282. The back film piece is longer than the front film piece. The back film piece has a top edge which is bonded to a top edge of header strip 280 at seal 284. Furthermore, the upper portion of the side edges of the back film piece are bonded to side edges of header strip 280 at seals 286 and 288. In this configuration, that portion of spunbonded fibrous header strip 280 inside seals 282, 284, 286, and 288 serves as a vent to allow sterilizing vapor, such as ethylene oxide vapor, to enter the chamber and sterilize product 270.

The packaging article in FIG. 8 is not in accordance with the packaging article of the invention, in that the packaging article in FIG. 8 is neither (i) provided with a skirt outward of a heat seal, with the skirt comprising a tear initiator from which the packaging article can be opened by manually initiating and manually propagating the tearing open of the packaging article, nor is it (ii) made from a film that exhibits linear tear upon being manually torn from a tear initiator, nor is it (iii) made from at least one film provided with an imbalanced internal stress with the film being configured in the packaging article so that upon manually initiating and manually propagating a linear tear through the skirt and through the heat seal and down the front and back sides of the pouch, first and second torn film edges curl outwardly and away from the product, i.e., curl outwardly and away from the interior of the packaging article. However, upon modifying the prior art packaging article of FIG. 8 so as to provide it with the combination of features (i), (ii), and (iii), above, i.e., modifying it as described herein, the prior art packaging article could be transformed into a packaging article made from a packaging receptacle in accordance with the invention.

FIG. 9 is a schematic of a preferred process for making a flexible thermoplastic film to be used in accordance with the present invention. In FIG. 9, for simplicity only one extruder 300 is illustrated. However, in the making of, for example, a four layer coextruded blown film, there would normally be four extruders, with each extruder feeding a single die in a multilayer die stack containing at least four discrete dies stacked one atop another. In the event that two or more film layers are to have an identical polymeric composition, those two or more layers could be formed by splitting the stream of a single extruder, with each of the streams from the splitting being fed into a discrete die in the die stack. As illustrated in FIG. 9, extruder 300 supplies a stream of molten polymer to coextrusion die 302 for the formation of a film layer. Extruder 300 subjects the polymer pellets to sufficient pressure and heat to melt the polymer and thereby prepare it for extrusion through die 302.

Taking extruder 300 as an example, each of the extruders is preferably equipped with a screen pack 304, breaker plate 306, and a plurality of heaters 308. Each of the coextruded film layers is extruded between mandrel 310 and die 302, and the extrudate is cooled by cool air flowing from air ring 312. The resulting blown bubble 314 is thereafter guided into a collapsed configuration by nip rolls 316, via guide rolls 318. The collapsed tube 326 is optionally passed over treater bar 320, and is thereafter passed over idler rolls 322, and around dancer roll 324 which imparts tension control to collapsed tube 326, after which collapsed tube 326 is wound into roll 328 via winding mechanism 330.

Curl can be provided in monolayer films as well as multilayer films. Film curl is the result of the presence of imbalanced internal stress in the film as the film is left in an unrestrained state or a state of restraint which is less than the curling force. Imbalanced internal stress is present if, across the film cross-section, one or more portions of the film exhibit enough contraction or expansion force in the plane of the film relative to another portion of the film in the cross-section. If enough such imbalanced internal stress is present in the film, the film will exhibit curl if unrestrained. The force that causes curl is the force to contract or expand the length and/or width of the film, not the force to expand the thickness of the film.

A variety of interdependent factors affect whether any particular film exhibits curl, as well as the degree of curling exhibited by the film. While attempts have been made to understand the relationship between these interdependent factors, predicting whether any given new film will curl, which direction it will curl in, and how much curl it will exhibit, remains as much art as science as curl is not fully predictable. These interdependent factors that affect the presence and degree of curl include both the composition of the film and the manner in which the film is produced. Depending upon the manner of film production, the presence of a composition having one or more of the following properties, relative to other compositions in the film, other layers in the film, and/or other regions within the film, can affect the presence and degree of curl exhibited by the film: (i) higher or lower crystallinity, (ii) primary and secondary crystallization kinetics (e.g., plasticization of polyamide by water vapor), (iii) modulus, (iv) higher or lower coefficient of thermal expansion, (v) higher or lower freezing point, (vi) the gauge of the finished film, and (vii) layer arrangement, relative layer thickness, and absolute layer thickness. Curl can be generated or enhanced by providing a lack of balance, across the cross-section of the film thickness, with respect to at least any one or more of interdependent compositional factors (i) through (vii) above.

For example, asymmetrical coextruded film structures using materials with significantly different coefficients of thermal expansion will cause a film to curl. Polymers in coextruded film structures are in intimate contact while in the molten state. As the polymers are cooled to ambient temperature, some will shrink enough to cause the film to exhibit curl. A single layer of HDPE can produce curl as an outermost portion of the cools, solidifies, and shrinks relative to a remainder of the HDPE layer that remains in the molten state. As cooling occurs across the thickness of the HDPE layer, the layer acquires an imbalanced internal stress that causes the resulting film to exhibit cur. The thermal coefficient of linear expansion of various polymers provided in Table 1, below.

TABLE 1 Abbreviation Thermal Coefficient of Polymer for Polymer Expansion (1/° K E⁻⁶) Ethylene acrylic acid copolymer EAA about 150-200 Ethylene/ethyl acrylate copolymer EEA about 160-250 Ethylene/methyl EMA about 160-250 acrylate copolymer Ethylene/methacrylic EMAA about 150-200 acid copolymer Ethylene/vinyl acetate copolymer EVA about 150-200 Ethylene/vinyl alcohol copolymer EVOH about 110 High density polyethylene HDPE about 150-300 Ionomer resin ION about 150-250 Low density polyethylene LDPE about 150-200 Linear low density polyethylene LLDPE about 200 Polyamide PA about 70-100 Polycarbonate PC about 68 Polyethylene terephthalate PET about 55-100 Polypropylene PP about 81-100 Polystyrene PS about 70-80 Polyvinyl chloride PVC about 70-250 Polyvinylidene chloride PVDC about 190 Cyclic olefin copolymer (e.g., COC about 0.6 × 10⁻⁴/° C. ethylene norbornene copolymer)

A difference in shrinkage between the layers of an asymmetrical multilayer film can cause the film to exhibit some degree of curling. Although the film structures are generally determined by properties specified by the application, the location of the polymer in the film structure can influence the tendency of the film to curl. The polymer shrinkage will exert a stress on the film structure proportional to the shrinkage and the elastic modulus according to the following equation:

Stress=(expansion coefficient)×(temperature difference)×(elastic modulus)

In addition to the above interdependent compositional/physical property parameters, a wide variety of interdependent film production parameters can affect whether any particular film exhibits curl, as well as the degree of curling exhibited by the film. For example, decreasing the rate of quenching of the molten extrudate emerging from the die increases the resulting crystallinity of the polymer in the film, allowing those portions of the film quenched more slowly to crystallize more than portions of the film quenched more quickly, with the resulting potential to create stress across the thickness cross-section of the film, thereby providing the potential to produce curl and/or increase curl in the film.

During quenching, the volume change during cooling occurs in three phases. The first phase is in the melt, up to the freezing temperature. This phase is not likely to significantly contribute to the curl of the film since the polymer is still a fluid and can flow in response to imposed stresses. At the second stage, i.e., the freezing point, a change in volume occurs due to crystallization. For example, in polyethylene the volume change is proportional to the density, which is proportional to crystallization, as the higher density polyethylenes are, in general, also more highly crystalline. At the third stage, i.e., as the polymer continues to cool while the solid state, the polymer shrinks further. The slope of the volume change in the solid phase is correlated to the coefficient of thermal expansion.

The amount of draw down of the extrudate can also generate and/or increase film curl. The draw down ratio (“DDR”) is the ratio of the thickness of the die gap to the thickness of the solidified extrudate. DDR includes two components: the amount of machine direction draw (“MD” draw), and the amount of transverse direction draw (“TD” draw). In a hot-blown film process as illustrated in FIG. 8, the blow-up ratio (“BUR”) is the ratio of the diameter of the annular die from which the extrudate emerges, to the diameter of the bubble blown from the extrudate immediately after it emerges. The BUR represents the TD draw ratio, and is a component of the DDR, with the other component of DDR being the MD draw ratio. Increasing the DDR in the machine direction can be used to increase the level of curl in the MD. Similarly, increasing the DDR in the transverse direction, or increasing the BUR, can increase the level of curl in the TD. Increasing the DDR or BUR increases stresses throughout the extrudate, and can increase stress differences across the cross-section of the film thickness, which can generate and/or increase the curl exhibited by the resulting film.

Additional interdependent processing equipment factors and process factors that have the potential to cause a film to curl and/or increase the level of film curl, include the diameter of the die, the rate of material emerging from the die, the die gap size, the frost line height (the location at which residual stress is frozen in), the amount of polymer orientation (orientation may affect crystalline morphology).

In addition to the interdependent factors discussed above, curl can be produced in a laminated film by at least slightly stretching at least one layer of the laminate at the time of lamination, while at least one additional layer on the film is not stretched. As a result, after the lamination the film structure may exhibit curl towards the stretched film as it contracts following release of the stretching force. Stretching of one layer immediately prior to lamination can be carried out by, for example, stretching between slower and faster draw rollers.

Curl can also be produced by providing at least one heat-shrinkable layer such that upon the film is exposed to a heat source, the heat-shrinkable layer reduces in size and the film curls. For example, in some embodiments, suitable heat shrinkable layers can include, but are not limited to, at least one of the following, and blends thereof: ethylene homopolymer, ethylene/α-olefin copolymer, propylene co- and homo-polymer, amorphous poly-α-olefin copolymer, SBC, COC, EEA, EBA, ionomer resin, polyvinyl chloride, PA, PC, PET, copolyester, polyvinyl acetate, PS, polyacrylate, PA, poly(methyl methacrylate), polyacrylonitrile, polyethylene naphthalate, and combinations thereof. To induce shrink of the shrinkable layer, the film can, for example, be exposed to temperature of 90° C. to 180° C. for a time period of about 0.5 seconds to about 12 hours. After exposure to heat, the heat-shrinkable layer causes the multilayer film to exhibit an internal stress that results in a curled film. See, for example, U.S. Pat. Nos. 7,687,123; 7,517,569; and 6,610,392, each of which is hereby incorporated, in its entirety, by reference thereto.

Curl can be obtained by laminating a heat-shrinkable film to a film that has already been heat-set (i.e., annealed, to relax the polymer strands and substantially decrease or eliminate the free shrink of the film) before lamination, and thereafter exposing the resulting laminate to heat to induce the curl tendency in the film. Suitable heat-set oriented films can include, but are not limited to: 13503 (available from AET Films, New Castle Del., United States of America), Mylar® 822 (available from DuPont Teijin Films (Wilmington, Del., United States of America), and Capran® Emblem™ 1530 (available from Honeywell International, Inc., Morristown, N.J., United States of America).

A film exhibiting curl can also be prepared by coextruding a multilayer film that has at least one layer that either shrinks or expands when exposed to an outside stimulus, such as, but not limited to: water, water vapor, heat, time, other environmental conditions, etc. For example, curling tends to increase with age, i.e., as a function of time. As another example, a multilayer film can comprise a layer containing a polyamide which, if exposed to water vapor, expands as water vapor is absorbed into the polyamide layer. Assuming other layers of the multilayer film do not expand as the polyamide layer expands, the multilayer film can thereby acquire curl.

A film exhibiting curl can also be produced by heat-setting a flat film, or a flattened film tubing, after the film or film tubing has been configured in a desired curl position, such as while rolled up in the form of a roll. Upon being heat-set in the curl position, the polymer chains equilibrate or rearrange to the induced curl configuration as a result of deformation at the heat-setting temperature. If desired, the polymer can be maintained in the deformed state by maintaining a radial pressure. At the conclusion of heating, the roll of film can then be cooled while in the desired curl position, to ensure that the film maintains its resistance to loss of curl following the heat-setting process. Usually, the heat-setting temperature is lower than the melting point of most or all of the polymers in the film. The heat-setting process can involve heating for a period of from 0.1 second to 1 hour or more.

Curl can be measured by making two intersecting cuts in the film in the form of a “+”. The level of curl of the film is determined by measuring the radius of curvature of the four unrestrained film flaps formed by the two intersecting cuts. The smaller the radius of curvature, the greater the level of curl exhibited by the film.

As used herein, the phrase “linear tear property” refers to the property a film exhibits upon a manually-initiated, manually-propagated tear of the film along a tear line that is either in the machine direction (“MD”) or in the transverse direction (“TD”), with the tear being capable of being manual-propagated to the opposite edge of the packaging article along a tear line that, for a tear initiated in the MD, is within 0 degrees (i.e., directly in the MD) to within 15 degrees of the MD, or, for a tear initiated in the TD, along a tear line that is within 0 degrees (directly in the TD) to within 15 degrees of the TD. An MD tear line can be within 0 to 10 degrees of the MD, or within 0 to 5 degrees of the MD, or within 0 to 2 degrees of the MD, or within 0 to 1 degree of the MD, or within 0 to 0.5 degree of the MD. A TD tear line can be within 0 to 10 degrees of the TD, or within 0 to 5 degrees of the TD, or within 0 to 2 degrees of the TD, or within 0 to 1 degree of the TD, or within 0 to 0.5 degree of the TD.

As used herein, “tearing along a line to the opposite edge of the packaging article” refers to tearing along a line down the packaging article, the tear being manually-initiated from a tear initiator in a skirt along an edge of the packaging article, with the tear being manually-propagated to an opposing edge of the packaging article, the opposing edge of the packaging article corresponding with the opposite edge of the packaging receptacle from which the packaging article was made. The opposite edge of the packaging article is a film edge or a fold line established before the product is placed into the chamber within the packaging receptacle and before the top seal is made to close the packaging receptacle and form the packaging article. For example, in a packaging article made from an end-seal bag, as the tear initiator can be present in a skirt outward of the top seal or in a skirt outward of the bottom seal, the tear can go to the opposite edge, i.e., from a tear initiator in a skirt below the bottom seal to the top edge of the packaging article above the top seal, or from a tear initiator in a skirt above the top seal to the bottom edge of the packaging article below the bottom seal.

In a packaging article made from a side-seal bag, a tear initiator in a skirt above the top seal can be used to produce a tear down the length of the packaging article made from the side-seal bag, the tear being to the bottom edge of the packaging article, which is the bottom fold line in the side-seal bag. A tear initiator in a skirt outward of a first side-seal of the packaging article made from the side-seal bag can be used to produce a tear across the width of the side-seal bag, the tear being to the second side edge of the packaging article, which is a film edge corresponding with the second side edge of the side-seal bag. As with a packaging article made from a side seal bag, tears down the length of, and/or across the width of, packaging articles made from L-seal bags and pouches can be made from respective tear initiators in respective skirts outward of top seals, skirt(s) outward of the side seal(s), and skirts outward of the bottom seals.

A variety of incompatible polymer blends can provide linear tear character in heat-shrinkable films that have been shrunken around a product, as disclosed in US Pub. No. 2009-0116768-A1 (=U.S. Ser. No. 11/895,960), which is hereby incorporated, in its entirety, by reference thereto. Heat-shrinkable films have been oriented in the solid state, and accordingly have relatively large built-in internal stresses which cause the film to shrink upon being heated.

It has been discovered that providing linear tear character to hot-blown multilayer films, and other multilayer films which have a total free shrink at 185° F. of less than 10 percent using ASTM D2732, is different from providing shrunken heat-shrinkable multilayer films with linear tear character. More particularly, providing a hot-blown multilayer film with a layer comprising a blend that imparts linear tear character to a shrunken heat-shrinkable multilayer film, without more, does not necessarily provide linear tear character to a hot-blown multilayer film. It has been discovered that hot-blown multilayer films “J-tear” if there is not enough residual stress between the layer comprising the incompatible polymer blend and at least one adjacent layer. A “J-tear” is a tear that does not manually-propagate to the opposite side of the packaging article, but rather tears off to an edge of the packaging article other than the opposite side edge. J-tearing impairs removal of the product from the packaging article because the J-tear does not run the full length or the full width of the packaging article.

In hot blown films, and other films exhibiting a total free shrink at 185° F. of less than 10 percent using ASTM D2732, blends of incompatible polymers present in films made using a high degree of machine direction orientation imparted by the blown film process (i.e., by using a small blow up ratio “BUR”) have been found to provide the film with the desired linear tear property. It is believed that immiscible polymer blends are phase segregated (i.e., phase separated) into major and minor domains, and that the orientation of the blend in a hot blown film process orients the blend in the direction of extrusion, i.e., the MD. Using a small BUR, the major and minor domains of an immiscible blend become more highly MD oriented, improving the MD linear tear performance. The MD oriented domains of the immiscible blend facilitate the MD linear tear.

As used herein, the phrase “incompatible polymers” refers to two polymers (i.e., a blend of at least two polymers) that are incapable of forming a solution or even a stable two-phase blend, and that tend to separate after being mixed. When blended, incompatible polymers are not miscible with one another, and phase separate into a continuous domain and a discontinuous domain that may be finely dispersed. The presence of one or more film layers comprising a blend of incompatible polymers may assist, enhance, or even cause the linear tear property of the film used to make the packaging receptacle.

Incompatible polymer blends found to be useful for imparting the linear tear property to non-shrink films include: (i) low density polyethylene (“LDPE”) and ionomer resin, (ii) polybutylene and ionomer resin, (iii) ethylene/vinyl acetate copolymer and ionomer resin, (iv) linear low density polyethylene and ionomer resin, (v) low density polyethylene and styrene/butadiene copolymer, (vi) low density polyethylene and polybutylene, (vii) cyclic olefin copolymer (e.g., ethylene/norbornene copolymer, polystyrene, etc) and low density polyethylene, (viii) cyclic olefin copolymer and linear low density polyethylene, (ix) cyclic olefin copolymer and high density polyethylene, (xi) cyclic olefin copolymer and polypropylene, (x) cyclic olefin copolymer and polystyrene, (xi) cyclic olefin copolymer and styrene/butadiene copolymer, (xii) polybutylene and ethylene/vinyl acetate copolymer, (xiii) polybutylene and linear low density polyethylene, (xiv) polybutylene and high density polyethylene, (xv) ethylene/vinyl acetate copolymer and linear low density polyethylene, (xvi) ethylene/vinyl acetate and metallocene catalyzed linear low density polyethylene, (xvii) polybutylene and polyethylene, and (xviii) polybutylene and polyolefin.

Based on total layer weight, the incompatible polymer blend can be present in a monolayer film or a layer of a multilayer film at a level of at least 51 weight percent, or at least 60 weight percent, or at least 70 weight percent, or at least 80 weight percent, or at least 90 weight percent, or at least 95 weight percent, or at least 98 weight percent, or at least 99 weight percent, or 100 weight percent. Based on total film weight, the incompatible polymer blend can be present in the film in an amount of from about 30 to 80 weight percent, or 40 to 70 weight percent, or 45 to 70 weight percent, or 50 to 70 weight percent, or 55 to 70 weight percent.

The blend of LDPE and ionomer resin can, for example, contain from 55 to 88 weight % LDPE blended with 45 to 12 weight % ionomer resin, or from 60 to 85 weight % LDPE blended with from 40 to 15 weight % ionomer resin, or from 75 to 85 weight ° A) low density polyethylene blended with from 25 to 15 weight % ionomer resin; from 78 to 82 weight % low density polyethylene blended with from 22 to 18 weight % ionomer resin. Moreover, the more highly neutralized the ionomer resin, the more immiscible the ionomer resin is with LDPE, which also improves linear tear performance.

Hot-blown films and other non-shrinkable films can be provided with the linear tear property through the presence of incompatible (i.e., immiscible) polymer blends. However, imparting the linear tear property to multilayer hot blown films and other non-shrink multilayer films further requires the presence of a residual stress between the layer comprising the incompatible polymer blend and an adjacent film layer. Alternatively, the linear tear property can be provided without an incompatible polymer blend and without the presence of particulate material. Particular layer combinations such as layers made from low density polyethylene adhering to each side of a layer made from ionomer resin can provide a film having the stress needed to impart the linear tear property.

The use of the incompatible polymer blend can provide the linear tear property without the need to provide the film with a line of weakness. A line of weakness in the film can be difficult and/or expensive to produce, and/or difficult to make uniform throughout many packaging receptacles. The line of weakness also provides the packaging article with a weakened area that subjects the packaging article to an enhanced probability of unintended fracture. Thus, while a line of weakness can be provided to the packaging article to ensure the linear tear property, it is preferred that the film having the linear tear property not be provided with a line of weakness.

As used herein, the verb “to tear” refers to pulling an object apart by force. The noun “tear” refers to the resulting break in the object being torn. The tearing of the film results from placing the film under enough tension that it is pulled apart by the force. The pulling force is concentrated by the tear initiator, which allows a smaller pulling force to pull the film apart, i.e., tear the film.

The phrase “tear initiator”, as used herein, refers to any one or more of a variety of means that can be located in a skirt of a packaging article. A tear initiator allows manual tearing force to be concentrated on a point or small region of the film, so that tear initiation and tear propagation can be produced manually. A slit in the bag skirt, can serve as the tear initiator. Alternatively, the tear initiator can be a notch in a bag skirt or a rounded notch in the bag skirt, or a rectangular notch in the bag skirt, or a slit hole in the bag skirt or a round hole in the bag skirt, or a pointed oval hole in the bag skirt, or a rectangular hole in the bag skirt. Many shapes of slits and notches can serve as tear initiators. The tear initiator can be a member selected from the group consisting of a straight slit within the skirt, a straight slit extending to the outer edge, a curved slit within the skirt, a curved slit extending to the outer edge, a V-shaped notch in the outer edge, a U-shaped notch in the outer edge, and a Y-shaped notch-slit combination extending to the outer edge. The tear initiator can be oriented so that the tear can be manually initiated and manually propagated in a direction in which the film was extruded. The tear initiator can be oriented so that the tear can be manually initiated and manually propagated in a direction transverse to a direction in which the film was extruded.

The tear initiator can be a cut in the skirt or header of the packaging article. As used herein, the term “cut” refers to the penetration through the film, or shearing through the film, with a shearing means or edged instrument. Preferably the cut is made through both sides of the packaging article. The term “cut” is inclusive of both slits and notches. As used herein, the term “slit” refers to a cut through the film without the separation and removal of a piece of film from the packaging article. A slit can be from the edge of the packaging article (i.e., an “edge slit”) or internal, i.e., not extending to an edge (i.e., “internal slit” also referred to as a “slit hole”). The slit can be straight or curved or wavy.

The term “hole”, as used herein, includes both an internal puncture (i.e., internal hole) or internal cut (i.e., an internal slit) through the packaging article, as well as an internal cut that removes a piece of film from the article. The hole can utilize a straight cut or a curved cut. The hole can be round or square or rectangular or irregular in shape.

A “notch” is formed by a cut that removes a piece of film along an otherwise straight or smooth curved edge of an article skirt or tail, producing a point for stress concentration during the subsequent manual application of tearing force. A notch can be V-shaped or round or square or rectangular or oval or of any regular or irregular profile.

The slit or notch or hole in the skirt or tail can extend across at least 10 percent of the width of the skirt before the bag is shrunk; or at least 20 percent, or at least 30 percent or at least 40 percent, or at least 50 percent, or at least 60 percent, or at least 70 percent, or at least 80 percent, or at least 90 percent, of the width of the skirt or tail. The slit or notch or hole can angle inward, toward the center of the packaging article.

In end-seal and side-seal bags, as well as other packaging articles, a portion of the skirt is in a first lay-flat side of the article (e.g., bag), and a portion of the same skirt is in a second lay-flat side of the article (e.g., bag). The first lay-flat side of the skirt can have a first tear initiator, and the second lay-flat side of the skirt can have a second tear initiator.

The first tear initiator can overlap (i.e., be coincident with) the second tear initiator when the end-seal or side-seal bag (or any other packaging article) is in its lay-flat configuration, as well as in the shrunken package. Overlapping enhances the ease of simultaneously initiating and propagating the tears in the first and second sides of the packaging article. Moreover, the first tear initiator can coincide (i.e., be positioned directly over and correspond with in length and shape) with the second tear initiator when the packaging article is in its lay-flat configuration.

A single packaging receptacle can be provided with both a first tear initiator that is overlapping or coincident with the second tear initiator, as well as a third tear initiator that is overlapping or coincident with a fourth tear initiator. The first and second tear initiators can be positioned in a skirt or header portion of the packaging receptacle for making a manual tear in a machine direction, with the third and fourth tear initiators being positioned for making a manual tear in a transverse direction. The third and fourth tear initiators can be positioned in a skirt or a header.

As used herein, the terms “overlapping” and “coincident” are used with respect to the relative positioning of paired tear initiators both when the article is in its lay-flat configuration and/or after a product is placed in the article and the article sealed closed around the product. The term “coincident” refers to two paired tear initiators that are directly on top of one another. The term “overlapping” refers to two paired tear initiators that are close enough to one another that an effort to manually tear one side of the packaging article at one of the tear notches results in tearing both sides of the article, i.e., from each of the paired tear initiators. The phrase “substantially coincident” is used interchangeably with the term “overlapping”. Typically, tear initiators within one half inch of being coincident with one another are deemed to be “overlapping”.

As used herein, the phrase “manual” and the term “manually” are both used with reference to tearing with the hands alone i.e., without the need for a knife, scissors, or any other implement to assist with initiating or propagating tearing of the film. The term “manual” is used with respect to tear initiation, i.e., the manual starting of the tearing action, as well as with respect to tear propagation, i.e., the manual continuation (i.e., extension) of a tear that has been manually initiated.

In addition to the tear initiator, the packaging article can be provided with “grip assister”, also referred to herein as a “grip enhancer”. The grip assister can enhance the ease with which the film can be torn. The grip assister can be in one lay-flat side of the packaging article or in both lay-flat sides of the packaging article. The grip assister can be a hole in the skirt (and/or in the header), an integral extension of the skirt or header, or a separate film tab fastened to the skirt or header. The separate film tab can be made from a thermoplastic polymer, paper, or other material, and can be heat-shrinkable or non-heat-shrinkable. The packaging article can be provided with the combination of a tear-initiator and a grip-assister. For example, the skirt can have a slit as the tear-initiator and a hole as the grip-assister. The skirt can have a slit as the tear initiator and two holes providing serving as the grip assister. Alternatively, the grip assister can be a tab used in combination with a slit.

With respect to the tearing of the film from which the packaging article is made, as used herein the phrase “the tear is capable of being propagated . . . ” refers to the manner in which the film tends to propagate the tear when the bag is subjected to an ordinary manual opening thereof, i.e., the packaging article can be “gripped and ripped” or “gripped and torn” in the ordinary course of opening.

As used herein, the phrase “readily removed” is applied to the removal of a product from a packaging article surrounding or substantially surrounding the product. As used herein, the phrase “readily removed” refers to the manual removal of the product from within the confines of the packaging article without any further substantial amount of tearing, and without any substantial further permanent deformation of the film. As used herein, the phrase “substantial tearing of the film” refers to tearing greater than or equal to 2 millimeters in length. As used herein, the phrase “substantial permanent deformation of the film” refers to a permanent stretching of the film greater than or equal to 2 millimeters at any location on the film.

First and second linear tears can be manually-initiated and manually-propagated from a single tear initiator or a pair of coincident tear initiators. A pair of coincident tear initiators is, for example, a first tear initiator in a first lay-flat side of the skirt and a second tear initiator in the second lay-flat side of the same skirt, with the first and second tear initiators being aligned directly over top and underneath one another, with the first and second tears being manually-initiated and manually-propagated along first and second lines through the skirt and through the heat seal defining an inner edge of the skirt, and thereafter further propagating as first and second tears made along first and second tear lines down the respective first and second sides of the packaging article.

Upon making a first linear tear and a second linear tear from coincident tear initiators in respective first and second sides of a packaging article made from a film having the linear tear property, the packaging article is torn into two discrete pieces of film upon tearing through to the opposite edge of the packaging article. If the tear initiators are positioned so that the tears propagate down the center of the length or width of the packaging article, the tears result in two pieces of film have the same size. The first and second tear lines are along parallel lines. The distance between the first and second tear lines is measured by the width of the film between the tear lines. This width corresponds with the width of the packaging article if the tears are MD tears down the center of the packaging article.

However, for the opening and transfer of a sterile medical article from a non-sterile nurse to a sterile nurse, in some instances it is preferred to provide coincident tear initiators in a skirt beneath a bottom seal of an end-seal bag, with the coincident tear initiators being located near a folded side edge of the bag, i.e., well offset from the centerline down the center of the bag length. The coincident tear initiators can be, for example, 0.75 inch from the folded side edge. In this manner, upon manually-initiating and manually-propagating the first and second tears from these coincident tear initiators, the distance between the first and second tears is 1.5 inches, i.e., the tears are along parallel lines 1.5 inches apart as measured by the width of the film strip between the first and second tears. That is, a 1.5 inch wide strip of film is torn from the remainder of the packaging article. This relatively narrow strip of material can easily be removed from the packaging article, allowing the sterile nurse to remove the product from the opened packaging article. Similarly, in a packaging article made from a side-seal bag, the tears could be MD tears from a skirt above the top seal, with the tears being along a side edge of the packaging article. In a packaging article made from an L-seal bag or a pouch, the tear initiators can be positioned for MD tears made along a side edge, or TD tears made along a top edge or along a bottom edge. It can be advantageous to provide the packaging articles with one or more tear initiators positioned to make a tear along an edge of the packaging article, with the resulting distance between the first and second tears being, for example, from 0.125 to 6 inches, or from 0.25 to 4 inches, or 0.5 to 3 inches, or 1 to 2 inches.

As used herein, a film is considered to be non-heat-shrinkable if the film exhibits a total free shrink at 185° F. (i.e., the sum of the free shrink in the direction of film extrusion, measured at 185° F., plus the free shrink in the direction transverse to the direction of film extrusion, measured at 185° F.) of less than 10 percent, using ASTM D2732.

Films useful in the invention can be produced using a full coextrusion process, i.e., multilayer films having all layers extruded simultaneously from a multilayer die, for example using the hot blown film process illustrated in FIG. 9, described above. A coextrusion process can utilize a slot die or an annular die. Alternatively, a film substrate can be extruded and thereafter subjected to an extrusion coating process, as disclosed by U.S. Pat. No. 4,278,738, to Brax et al, which is hereby incorporated, in its entirety, by reference thereto. Still further, the film can be produced using a cast process followed by quenching (either as a fully coextruded film or in conjunction with extrusion coating after quenching of the extrudate from an annular or slot die), followed by solid state orientation, resulting in a film that is heat-shrinkable due to the solid-state orientation, as disclosed in U.S. Pat. No. 8,012,520, which is hereby incorporated, in its entirety, by reference thereto. Moreover, heat shrinkable films can be heatset (i.e., annealed) to reduce or remove the heat-shrinkable property if it is desired that the film does not exhibit heat shrinkability.

Examples 1-29

Examples 1-29 pertain to multilayer films made using a hot-blown films process as illustrated in FIG. 9, described above. The hot-blown film line used to make the films of Examples 1 through 29 were made using a die having a 15 inch diameter, with a die gap of 101 mils. The process was carried out so that 180.2 pounds/hr of material was emitted from the multilayer die. The BUR was 1.3. The film had a lay-flat width of 30.6 inches. The nip rollers at the top of the bubble had a surface speed of 39 feet per minute. Air emitted from the quenching air ring was at 53.3° F.

As hot-blown films, each of the films of Examples 1 through 29 are believed to have exhibited a total (i.e., MD+TD) free shrink at 185° F. of less than 10 percent. These examples were run in order to make a film that exhibited the combination of both linear tear and curl. The various resins used in Examples 31 through 37 are set forth in Table 2, below.

TABLE 2 Resin name Melt index Density in film table Composition Supplier Tradename (dg/min) (g/cc) LD LDPE LyondellBasell Petrothene 1.8 0.921 NA345013 LLD#1 et/C₈ copolymer Dow Dowlex 2045 1 0.922 (linear low density polyethylene) LLD#2 et/C₄ copolymer ExxonMobil LL1001X26 1.1 0.918 (linear low density polyethylene) mEAO Homogeneous ExxonMobil Exceed 1012CJ 1.0 0.912 et/C₆ copolymer ION#1 Ionomer resin #1 DuPont Surlyn 1601-2 1.3 0.942 ION#2 lonomer resin #2 Dow Amplify 3801B 1.25 0.94 COC Ethylene/norbornen

Topas 8007 30 1.02 copolymer PS Polystyrene Nova Ineos 1600 5.5 1.04 s&a/b Slip agent and Ampacet 100622 8 0.92 antiblocking agent in LDPE HD HDPE Nova 19C 0.95 0.958

indicates data missing or illegible when filed

TABLE 3 Examples 1-29 Example Inside Skin Thickness No. & Seal Core Layer Outside Skin (mils) Comment 1 78% LD 75% LD 70% HD 4 Good linear tear and (working) 20% LLD#1 25% ION#1 20% LLD#1 curl, but would not 2% s&a/b 2.4 mil 8% LD heat seal to 0.8 mil 2% s&a/b spunbonded vent 0.8 mil sheet 2 78% LD 75% LD 70% HD 3 Good linear tear and (working) 20% LLD#1 25% ION# 1 20% LLD#1 curl, but would not 2% s&a/b 1.8 mil 8% LD heat seal to 0.6 mil 2% s&a/b spunbonded vent 0.6 mil sheet 3 78% LD 75% mEAO 70% HD 3.6 Good linear tear and (working) 20% LLD#1 25% ION#1 20% LLD#1 curl, but would not 2% s&a/b 2.4 mil 8% LD heat seal to 0.6 mil 2% s&a/b spunbonded vent 0.6 mil sheet 4 78% LD 75% mEAO 70% HD 4 Good linear tear and (working) 20% LLD# 1 25% LLD#2 20% LLD#1 curl, but would not 2% s&a/b 2.4 mil 8% LD heat seal to 0.8 mil 2% s&a/b spunbonded vent 0.8 mil sheet 5 78% LD 75% LD 50% HD 3 Good linear tear and (working) 20% LLD#1 25% ION#1 28% LD curl, but would not 2% s&a/b 1.8 mil 20% LLD#1 heat seal to 0.6 mil 2% s&a/b spunbonded vent 0.6 mil sheet 6 78% LD 75% LD 50% HD 4 Good linear tear and (working) 20% LLD#1 25% ION#1 28% LD curl, but would not 2% s&a/b 2.4 mil 20% LLD#l heat seal to 0.8 mil 2% s&a/b spunbonded vent 0.8 mil sheet 7 78% LD 70% LLD#1 50% HD 3 Good linear tear and (working) 20% LLD#1 30% COC 28% LD curl, but would not 2% s&a/b 1.5 mils 20% LLD#1 heat seal to 0.5 mil 2% s&a/b spunbonded vent 0.6 mil sheet Example Inside Skin Thickness No. & Seal Core #3 Outside Skin (mils) Comment  8 78% LD 70% LLD#1 70% HD 3 Good linear tear and (working) 20% LLD#1 30% COC 20% LLD#1 curl, but would not 2% s&a/b 1.5 mils 8% LD heat seal to 0.5 mil 2% s&a/b spunbonded vent 0.6 mil sheet  9 78% LD 90% LLD#1 78% LD 3 Good linear tear and (working) 20% LLD#1 10% COC 20% LLD#1 curl, but would not 2% s&a/b 1.8 mils 2% s&a/b heat seal to 0.6 mil 0.6 mil spunbonded vent sheet 10 78% LD 90% LLD#1 78% LD 2.5 Good linear tear and (working) 20% LLD#1 10% COC 20% LLD#1 curl, but would not 2% s&a/b 1.5 mils 2% s&a/b heat seal to 0.5 mil 0.5 mil spunbonded vent sheet 11 78% LD 80% LLD#1 78% LD 3 Good linear tear and (working) 20% LLD#1 20% COC 20% LLD#1 curl, but would not 2% s&a/b 1.8 mils 2% s&a/b heat seal to 0.6 mil 0.6 mil spunbonded vent sheet 12 78% LD 80% LLD#1 78% LD 2.5 Good linear tear and (working) 20% LLD#1 20% COC 20% LLD#1 curl, but would not 2% s&a/b 1.5 mils 2% s&a/b heat seal to 0.5 mil 0.5 mil spunbonded vent sheet 13 78% LD 70% LLD#1 78% LD 3 Good linear tear and (working) 20% LLD#1 30% COC 20% LLD#1 curl, but would not 2% s&a/b 1.8 mils 2% s&a/b heat seal to 0.6 mil 0.6 mil spunbonded vent sheet 14 78% LD 70% LLD#1 78% LD 2.5 Good linear tear and (working) 20% LLD#1 30% COC 20% LLD#1 curl, but would not 2% s&a/b 1.5 mils 2% s&a/b heat seal to 0.5 mil 0.5 mil spunbonded vent sheet 15 78% LD 85% LD 78% LD 3 No curl (working) 20% LLD#1 15% ION#1 20% LLD#1 2% s&a/b 1.8 mil 2% s&a/b 0.6 mil 0.6 mil 16 78% LD 85% LD 78% LD 4 No curl; but tears via (working) 20% LLD#1 15% ION#1 20% LLD#1 ionomer 2% s&a/b 2.4 mil 2% s&a/b 0.8 mil 0.8 mil 17 78% LD 75% LD 78% LD 3 No curl; but tears via (working) 20% LLD#1 25% ION#1 20% LLD#1 ionomer 2% s&a/b 1.8 mil 2% s&a/b 0.6 mil 0.6 mil 18 78% LD 75% LD 78% LD 4 No curl; but tears via (working) 20% LLD#1 25% ION#1 20% LLD#1 ionomer 2% s&a/b 2.4 mil 2% s&a/b 0.8 mil 0.8 mil 19 78% LD 60% LD 78% LD 3 No curl; but tears via (working) 20% LLD#1 40% ION#1 20% LLD#1 ionomer 2% s&a/b 1.8 mil 2% s&a/b 0.6 mil 0.6 mil 20 78% LD 60% LD 78% LD 4 No curl; but tears via (working) 20% LLD#1 40% ION#1 20% LLD#1 ionomer 2% s&a/b 2.4 mil 2% s&a/b 0.8 mil 0.8 mil 21 78% LD 80 LD 78% LD 3 mils No Curl (compar.) 20%LLD#1 20% ION#2 20% LLD#1 Exhibits Linear Tear 2% s&a/b 1.8 mil 2% s&a/b 0.6 mil 0.6 mil Example Outer Internal Internal Outer Gauge No.. layer Layer Layer Layer (mils) Comment 22 78% LD 78% LD 100% HD 78% LD 3 mils Good linear tear and (working) 20% LLD#1 20% ION#2 0.6 mil 20% LLD#1 curl, but would not 2% s&a/b 2% s&a/b 2% s&a/b heat seal to 0.6 mil 1.2 mil 0.6 mil spunbonded vent sheet 23 78% LD 78% LD 50% HD 78% LD 3 mils J-tears; no curl due (compar.) 20% LLD#1 20% ION#2 50% PS 20% LLD#1 to no residual stress 2% s&a/b 2% s&a/b 0.6 mil 2% s&a/b between internal 0.6 mil 1.2 mil 0.6 mil layers; HDPE layer delaminated from adjacent layers 24 78% LD 78% LD 70% 78% LD 3 mils Good linear tear, (working) 20% LLD#1 20% ION#2 LLD#1 20% LLD#1 low curl, but some 2% s&a/b 2% s&a/b 30% COC 2% s&a/b curl, but would not 0.6 mil 1.2 mil 0.6 mil 0.6 mil heat seal to spunbonded vent sheet Example Total No. Outer layer Internal Layer Outer Layer Thickness Comments 25 78% LD 80% LD 78% LD 3 mils no curl; (compar.) 20% LLD#1 20% ION#1 20% LLD#1 exhibited linear tear 2% s&a/b 1.8 mils 2% s&a/b 0.6 mil 0.6 mil 26 78% LD 80% LD 78% LD 4 mils no curl (compar.) 20% LLD#1 20% ION#1 20% LLD#1 exhibited linear 2% s&a/b 2.4 mils 2% s&a/b tear 0.8 mil 0.8 mil 27 78% LD 60% LD 78% LD 3 mils no curl; (compar.) 20% LLD#1 40% ION#1 20% LLD#1 exhibited linear 2% s&a/b 1.8 mils 2% s&a/b tear 0.6 mil 0.6 mil 28 78% LD 60% LD 78% LD 4 mils no curl; (compar.) 20% LLD#1 40% ION#1 20% LLD#1 exhibited linear 2% s&a/b 2.4 mils 2% s&a/b tear 0.8 mil 0.8 mil 29 78% LD 80% LD 78% LD 3 mils no curl; (compar.) 20% LLD#1 20% ION#2 20% LLD#1 exhibited linear 2% s&a/b 1.8 mils 2% s&a/b tear 0.6 mil 0.6 mil 30 78% LD 80% LD 78% LD 4 mils no curl; (compar.) 20% LLD#1 20% ION#2 20% LLD#1 exhibited linear 2% s&a/b 2.4 mils 2% s&a/b tear 0.8 mil 0.8 mil

Examples 31 through 37 Examples 31-37 pertain to multilayer films made using a hot-blown films process as illustrated in FIG. 9, described above. The hot-blown film line used to make the films of Examples 31 through 37 had a 15 inch diameter annular die with a die gap of 101 mils. The process was carried out so that 192 pounds/hr of material was emitted from the multilayer die. The BUR was 1.43 and the DDR was 12.02. The MD-TD draw ratio was 9.12. The cooling time was 2.10 seconds. The film gauge was 3 mils and the frost line height (“FLH”) was about 20 inches from emergence of the melt stream from the die. The initial velocity (V₀) of the melt streams at the die gap was 0.948 inches per second. The final velocity (V_(f)) of the hot blown film was 35.54 inches per second. The strain rate 1.73 sec⁻¹. The various fabrication parameters are related as follows:

Drawdown=Gap/Gauge/BUR

MD/TD Ratio=DDR/BUR

Cooling Time=FLH/(V _(f) −V ₀)·ln(V _(f) /V ₀)

Strain Rate=(V _(f) −V ₀)/FLH

Shear Rate=6Q/(π·D·Gap²)

As hot-blown films, each of the films of Examples 31 through 37 are believed to have exhibited a total (i.e., MD+TD) free shrink at 185° F. of less than 10 percent. These examples were run in order to make a film that exhibited the combination of both linear tear and curl, while also being heat sealable to itself as well as heat sealable to a spunbonded fibrous web such as Tyvek® brand flashspun high-density polyethylene fibrous sheet material as well as being heat sealable to paper.

In Examples 31-37, the films having layers containing a blend of 60% LDPE and 40% sodium ionomer resin (an immiscible blend) consistently provided the best linear tear performance. The SBC/HDPE resin blend provided the highest degree of curl among the various resins used in examples 31-37.

In Example 36, the 60% LDPE/40% sodium ionomer resin immiscible blend, when coextruded with the SBC/HDPE blend, provided the film having the best combination of linear tear with curl performance. In Example 36, interfacial instability was observed in the film structure due to a mismatch in rheology between layers. Example 36 also had an asymmetrical, unbalanced layer distribution, and had layers containing polymers having significantly different coefficients of thermal expansion (hence differential shrinkage) between adjacent layer, which generated residual stress between layers and resulted in curl. Also, in Example 36 there was a significant difference in the modulus of the resins used in adjacent layers, which enhanced the curl performance. The torn edges of the first and second tears in Example 36 were “clean tears” in that the torn film edges did not exhibit “scalloping”, i.e., rippled edges. Rippled edges are undesirable in that they do not curl as well as cleanly torn edges. Moreover, rippled edges also provide a greater opportunity for contamination during product removal from the packaging article. In addition, Example 36 exhibited relatively low tear resistance, a desirable property. However, in Example 36 the HDPE in the SBC blend created some haziness.

In Examples 31-37, the immiscible blend of LDPE and sodium ionomer resin provided the best linear tear performance. Curl was provided by unbalancing the modulus, thickness, crystallinity, and coefficients of thermal expansion of the compositions used in adjacent layers. The various resins used in Examples 31 through 37 are set forth in Table 4, below.

TABLE 4 Resins Used in Examples 31 through 37 Melt index Density VA T_(c) 1% Sec. Resin Tradename Supplier (dg/m) (g/cm³) (%) (° C.) Mod, (PSI) mVLDPE Exceed 1012CJ Exxon 1 0.912 102 19000 Escorene LD EVA-1 721.1K Exxon 2.55 0.942 18.5 72 9200 ESCORENE LD EVA-2 713.93 Exxon 3.5 0.933 14.4 74 9500 COC 8007 Topas 2 1.02 78 SBC Styrolux HS70 BASF 13 1.02 230 202000 PA-6 Ultramid B40 BASF 1.13 220 lonomer AMPLIFY 3801B Dow 1.3 0.94 95 LDPE NA345 LB1 1.8 0.921 LLDPE Tie Plexar 3236 MIS 2 0.921 s&a/b 10850 Ampacet 1.8 0.95 LLDPE Dowlex 2045 Dow 1 0.921 122 HDPE 19C Nova 0.95 0.958 121830 EVA TIE Bynel 3861 DuPont 2 0.98 25.0 Nova PS 1600 Ineos 5.5 1.04

TABLE 5 Example 31 (Comparative) First layer 2^(nd) layer 3^(rd) layer 4^(th) layer 5^(th) layer 6^(th) layer Composition 100% 40% 100% 100% 100% 78% LDPE HDPE Ionomer LLDPE TIE PA-6 LLDPE TIE 20% LLDPE 60% LDPE 2% s&ab Intended Layer curl linear tear Tie curl Tie Seal function Thickness 10 55 7.5 10 7.5 10 (% of total) Gauge (mils) 0.3 1.65 0.225 0.3 0.225 0.3 Linear Tear Property: film of example 31 exhibited J-tear Curl: film of example 31 was flat Example 32 (Comparative) 1^(st) layer 2^(nd) layer 3^(rd) layer 4^(th) layer Composition 100% HDPE 40% Ionomer 30% COC 78% LDPE 60% LDPE 70% LLDPE 20% LLDPE 2% s&ab Intended Layer Curl linear tear Curl Seal function Thickness 10 60 20 10 (% of total) Gauge (mils) 0.3 1.8 0.6 0.3 Linear Tear Property: film of example 32 exhibited linear tear Curl: film of example 32 was flat because the 1^(st) and 3^(rd) layers canceled each other out Example 33 (Comparative) 1^(st) layer 2^(nd) layer 3^(rd) layer 4^(th) layer Composition 100% HDPE 40% Ionomer 70% SBC 78% LDPE 60% LDPE 30% EVA-1 20% LLDPE 2% s&ab Intended Layer Curl linear tear Curl Seal function Thickness 10 60 20 10 (% of total) Gauge (mils) 0.3 1.8 0.6 0.3 Linear Tear Property: film of example 33 exhibited linear tear Curl: film of example 33 was flat because the 1^(st) and 3^(rd) layers canceled each other out Example 34 (Comparative) 1^(st) layer 2^(nd) layer 3^(rd) layer 4^(th) layer Composition 100% HDPE 60% mVLDPE 30% COC 78% LDPE 30% EVA 70% LLDPE 20% LLDPE 10% COC 2% s&ab Intended Layer Curl Linear tear Curl Seal function Thickness 10 60 20 10 (% of total) Gauge (mils) 0.3 1.8 0.6 0.3 Linear Tear Property: film of example 34 did not exhibit linear tear Curl: film of example 34 exhibited very low curl level because the 1^(st) and 3^(rd) layers canceled each other out Example 35 (Working) 1^(st) layer 2^(nd) layer 3^(rd) layer 4^(th) layer Composition 78% LDPE 40% ionomer 100% HDPE 78% LDPE 20% LLDPE 60% LDPE 20% LLDPE 2% s&a/b 2% s&ab Intended Layer Seal Linear tear Curl Seal function Thickness 10 60 20 10 (% of total) Gauge (mils) 0.3 1.8 0.6 0.3 Tear Property: film of example 35 exhibited linear tear, due to 2^(nd) layer Curl: film of example 35 exhibited a low level of curl from the HD layer; curl could have been increased by adjusting process conditions (BUR, quench rate, freezing point, etc.) Example 36 (Working) 1^(st) layer 2^(nd) layer 3^(rd) layer 4^(th) layer Composition 78% LDPE 40% ionomer 50% HDPE 78% LDPE 20% LLDPE 60% LDPE 50% SBC 20% LLDPE 2% s&a/b 2% s&ab Intended Layer Seal Linear tear Curl Seal function Thickness 10 60 20 10 (% of total) Gauge (mils) 0.3 1.8 0.6 0.3 Tear Property: film of example 36 exhibited good linear tear Curl: film of example 36 exhibited good curl (up to 180 degrees along tear line) Example 37 (Comparative) 1^(st) layer 2^(nd) layer 3^(rd) layer 4^(th) layer 5^(th) layer 6^(th) layer Composition 100% 40% 100% 100% PS 100% 78% LDPE HDPE ionomer EVA TIE EVA TIE 20% LLDPE 60% LDPE 2% s&ab Intended Layer Curl linear tear Tie Curl Tie Seal function Thickness 10 55 7.5 10 7.5 10 (% of total) Gauge (mils) 0.3 1.65 0.225 0.3 0.225 0.3 Linear Tear Property: film of example 37 exhibited J-tear Curl: film of example 37 exhibited a fair curl level, due to differential quench of the PS layer, but the film of example 37 delaminated, as the 4^(th) layer delaminated from 3^(rd) layer and 5^(th) layer due to PS not bonding with EVA TIE layers

The various features disclosed herein can be used in any desired combination so long as they are not incompatible with one another. For example, the features recited in the various accompanying dependent claims make up a set of features that can all be used in combination together in a single embodiment, at least to the extent that these features are not mutually exclusive, inconsistent, or incompatible with one another. Alternatively, any subset of this set of features can be used in a single embodiment, to the extent that this subset of features is are not mutually exclusive, inconsistent, or incompatible with one another. Of course, the various additional features disclosed but not claimed herein can also be used together in a single embodiment or in combination in any subset thereof, alone as a set or in any desired combination with all other features disclosed herein (including claimed herein), at least the extent that the resulting combination of features does not include a combination or subcombination of mutually exclusive, inconsistent, or incompatible features. 

What is claimed is:
 1. A packaging receptacle for making a manually-openable package for packaging a product, the packaging receptacle being made from a flexible film, the packaging receptacle comprising: (A) a first side sealed to a second side at a first seal; (B) a top edge and an open top so that the product can be inserted into an interior chamber within the packaging receptacle; (C) a tear initiator; wherein the flexible film has both a linear tear property and an imbalanced internal stress, so that upon placing a product into the packaging receptacle and sealing the packaging receptacle closed with a top seal to form a packaging article around the product, the tear initiator is present in a skirt which is outward of the first seal or outward of the top seal, and upon manually initiating a tear from the tear initiator, the tear is manually propagated through the first seal or the top seal, with the tear thereafter further propagating as both a first tear and a second tear, the first tear being down the first side of the packaging article and the second tear being down the second side of the packaging article, with the manual propagation of the tear down the first side producing first and second torn edges, and the manual propagation of the tear down the second side producing third and fourth torn edges, wherein film along at least the first torn edge and the second torn edge curls outwardly and away from the interior chamber within the packaging article.
 2. The packaging receptacle according to claim 1, wherein the film has a total free shrink at 85° C. of less than 10 percent, measured in accordance with ASTM D2732
 3. The packaging receptacle according to claim 1, wherein the tear initiator is positioned so that the first and second tears are made along parallel lines, with the distance between the first and second tear lines being from 0.125 to 6 inches.
 4. The packaging receptacle according to claim 1, wherein the film is a multilayer film and at least one layer of the multilayer film comprises a blend making up at least 51 percent of the layer weight, the blend being at least one member selected from the group consisting of (i) low density polyethylene and ionomer resin, (ii) polybutylene and ionomer resin, (iii) ethylene/vinyl acetate copolymer and ionomer resin, (iv) linear low density polyethylene and ionomer resin, (v) low density polyethylene and styrene/butadiene copolymer, (vi) low density polyethylene and polybutylene, (vii) cyclic olefin copolymer and low density polyethylene, (viii) cyclic olefin copolymer and linear low density polyethylene, (ix) cyclic olefin copolymer and high density polyethylene, (xi) cyclic olefin copolymer and polypropylene, (x) cyclic olefin copolymer and polystyrene, (xi) cyclic olefin copolymer and styrene/butadiene copolymer, (xii) polybutylene and ethylene/vinyl acetate copolymer, (xiii) polybutylene and linear low density polyethylene, (xiv) polybutylene and high density polyethylene, (xv) ethylene/vinyl acetate copolymer and linear low density polyethylene.
 5. The packaging receptacle according to claim 1, wherein the film is a multilayer film, and comprises: a linear tear layer providing the multilayer film with the linear tear property, the linear tear layer making up from 50 to 70 percent of the total film thickness, the linear tear layer comprising an incompatible polymer blend that makes up from 80 to 100 weight percent of the linear tear layer; a curl layer that provides the film with the imbalance of internal stress, the curl layer making up from 15 to 35 percent of the total film thickness, the curl layer comprising at least one member selected from the group consisting of high density polyethylene, styrene/butadiene copolymer, polystyrene, ethylene/norbornene copolymer, polyamide, polyester; and at least one outer heat-sealable layer comprising at least one member selected from the group consisting of ethylene homopolymer, ethylene/alpha-olefin copolymer, ionomer resin, and ethylene/unsaturated ester copolymer, the outer heat-sealable layer having a thickness of at least 5 percent of the total film thickness.
 6. The packaging receptacle according to claim 1, wherein the film along the third torn edge curls away from the interior chamber within the packaging article, and the film along the fourth torn edge curls away from the interior chamber within the packaging article.
 7. The packaging receptacle according to claim 1, wherein the skirt is outward of the first seal, and the tear initiator is present in the skirt.
 8. The packaging receptacle according to claim 1, wherein the skirt is outward of the top seal, and the tear initiator is present in the skirt.
 9. The packaging receptacle according to claim 1, wherein the first and second tears can be manually propagated down the length of the packaging article to an opposite edge of the packaging article.
 10. The packaging receptacle according to claim 1, wherein at least one lay-flat side of the packaging receptacle further comprises a vent comprising a continuous film edge defining a vapor passageway into the interior of the packaging receptacle, with a semi-permeable membrane covering the vapor passageway, the semi-permeable membrane overlapping the film in a rim region around the passageway, with the semi-permeable membrane being bonded to the film around an entirety of a perimeter of the passageway, and wherein the vent is positioned so that neither the first tear down the first lay-flat side of the article nor the second tear down the second lay-flat side of the packaging article propagates into or through the vent.
 11. The packaging receptacle according to claim 10, wherein the semi-permeable membrane comprises a spun-bonded high density polyethylene fibrous sheet, and the film is heat sealed to the semi-permeable membrane.
 12. The packaging receptacle according to claim 10, wherein the packaging receptacle comprises a first vent and a second vent, with the first vent being separated from the second vent by a distance of from 5 centimeters to 50 centimeters.
 13. The packaging receptacle according to claim 12, further comprising a third vent and a fourth vent, with each of the first, second, third, and fourth vents being separated from the other vents by a distance of at least 2 centimeters.
 14. The packaging receptacle according to claim 1, further comprising a first grip-assister on a first side of the tear initiator and a second grip-assister on a second side of the tear initiator, each of the first and second grip assisters comprising a continuous interior film edge defining a passageway through the skirt of the packaging receptacle.
 15. The packaging receptacle according to claim 1, wherein the packaging receptacle is an end-seal bag comprising a seamless film tubing in lay-flat configuration with the first seal being a first heat seal forming a bottom of the interior chamber within the end-seal bag, with the end-seal bag having a folded first side edge and a folded second side edge, and wherein upon placing a product into the end-seal bag and sealing the end-seal bag closed with the top heat seal, the end-seal bag forms a packaging article around the product, with the tear initiator being present in the skirt which is outward of the first heat seal or outward of the top heat seal, and upon manually initiating a tear from the tear initiator, the tear can be manually propagated through the first heat seal or the top heat seal, with the tear thereafter further propagating as both the first tear and the second tear, the first tear being down the first lay-flat side of the packaging article and the second tear being down the second lay-flat side of the packaging article, with the manual propagation of the tear down the first lay-flat side producing first and second torn edges, and the manual propagation of the tear down the second lay-flat side producing third and fourth torn edges, wherein film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.
 16. The packaging receptacle according to claim 1, wherein the packaging receptacle is a side-seal bag comprising a flat film having a folded bottom edge, with the film on a first side of the fold making up the first lay-flat side of the side-seal bag and the film on a second side of the fold making up the second lay-flat side of the side-seal bag, with the first seal being a first side seal along a first side edge of the bag, the first side seal being a heat seal, the first side seal extending from the folded bottom edge of the side-seal bag to the top edge of the side-seal bag, with the side-seal bag further comprising a second side seal along a second side edge of the bag, the second side seal also being a heat seal, the second side seal extending from the folded bottom edge of the side-seal bag to the top edge of the side-seal bag, and wherein upon placing a product into the side-seal bag and sealing the side-seal bag closed with the top seal, the side-seal bag forms a packaging article around the product, with the tear initiator being present in the skirt which is outward of the first side seal or outward of the second side seal, or outward of the top seal, and upon manually initiating a tear from the tear initiator, the tear can be manually propagated through the respective first heat seal or the second heat seal or the top seal, with the tear thereafter further propagating as both the first tear and the second tear, the first tear being down the first lay-flat side of the packaging article and the second tear being down the second lay-flat side of the packaging article, with the manual propagation of the tear down the first lay-flat side producing first and second torn edges, and the manual propagation of the tear down the second lay-flat side producing third and fourth torn edges, wherein film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.
 17. The packaging receptacle according to claim 1, wherein the packaging receptacle is an L-seal bag comprising a flat film having a fold therein, with the fold providing a first side edge of the L-seal bag, with the film on a first side of the fold making up the first lay-flat side of the L-seal bag and the film on a second side of the fold making up the second lay-flat side of the L-seal bag, with the fold extending from a bottom edge of the L-seal bag to the top edge defining the open top of the L-seal bag, with the first seal being a first heat seal which is an end seal forming a bottom of the interior chamber of the L-seal bag, the first heat seal being along a bottom edge of the L-seal bag, the first heat seal extending from the first side edge of the L-seal bag to a second side edge of the L-seal bag, with the L-seal bag further comprising a second heat seal along a second side edge thereof, the second heat seal extending from the bottom edge of the L-seal bag to the top edge of the L-seal bag, and wherein upon placing a product into the L-seal bag and sealing the L-seal bag closed with the top seal, the L-seal bag forms a packaging article around the product, with the tear initiator being present in the skirt which is outward of the first heat seal or the second heat seal or the top seal, and upon manually initiating a tear from the tear initiator, the tear can be manually propagated through the respective first heat seal or second heat seal or top seal, with the tear thereafter further propagating as both the first tear and the second tear, the first tear being down the first lay-flat side of the packaging article and the second tear being down the second lay-flat side of the packaging article, with the manual propagation of the tear down the first lay-flat side producing first and second torn edges, and the manual propagation of the tear down the second lay-flat side producing third and fourth torn edges, wherein film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.
 18. The packaging receptacle according to claim 17, wherein: the skirt is a first skirt which is outward of the first heat seal and the tear initiator is a first tear initiator present in the first skirt, the L-seal bag further comprises a second skirt outward of the second heat seal, with a second tear initiator in the second skirt, the second tear initiator being in a position to make a linear tear along the top heat seal of the packaging article, so that upon initiating first and second linear tears across the first and second lay-flat sides of the packaging article from the second tear initiator to the opposite edge of the packaging article, with the first and second tears being manually-propagated across a width of the packaging article, and thereafter initiating third and fourth linear tears down the first and second lay-flat sides of the packaging article from the first tear initiator, with the third and fourth tears being manually-propagated down the length of the packaging article to the opposite edge of the packaging article, a first unrestrained corner flap is produced on the first lay-flat side of the packaging article, and a second unrestrained corner flap is produced on the second lay-flat side of the packaging article, with the unrestrained corner flaps being capable of curling all the way back to a diagonal line extending from a torn end of the first heat seal to a torn end of the second heat seal, thereby exposing the product within the chamber of the packaging article.
 19. The packaging receptacle according to claim 1, wherein the packaging receptacle is a pouch and the first lay-flat side is a discrete first film panel and the second lay-flat side is a discrete second film panel, and the first seal is a heat seal which is an end seal forming a bottom of the interior of the packaging receptacle, the end seal extending along a bottom edge of the pouch, the end seal extending from a first side edge of the pouch to a second side edge of the pouch, the pouch further comprising a second heat seal along a first side edge of the pouch, with a second heat seal extending from the bottom edge of the pouch to the top edge of the pouch that defines the open top of the pouch, the pouch further comprising a third heat seal along a second side edge of the pouch, with the third heat seal also extending from the bottom edge of the pouch to the top edge of the pouch, and wherein upon placing a product into the pouch and sealing the pouch closed with the top seal, the pouch bag forms a packaging article around the product, with the tear initiator being present in the skirt which is outward of the first heat seal or the second heat seal or the third heat seal or the top seal, and upon manually initiating a tear with the tear initiator being present in the skirt which is outward of the first heat seal or the second heat seal or the third heat seal or the top seal, the tear can be manually propagated through the respective end seal or the first heat seal or the second heat seal, or the third heat seal or the top seal, with the tear thereafter further propagating as both the first tear and the second tear, the first tear being down the first lay-flat side of the pouch and the second tear being down the second lay-flat side of the pouch, with the manual propagation of the first tear down the first lay-flat side producing first and second torn edges, and the manual propagation of the second tear down the second lay-flat side producing third and fourth torn edges, wherein film along the first and second torn edges curls outwardly and away from the interior chamber within the packaging article, and film along the third and fourth torn edges also curls outwardly and away from the interior chamber within the packaging article.
 20. The packaging receptacle according to claim 19, wherein: the skirt is a first skirt which is outward of the first heat seal and the tear initiator is a first tear initiator present in the first skirt, the pouch further comprises a second skirt outward of the second heat seal, with a second tear initiator in the second skirt, the second tear initiator being in a position to make a linear tear along the top heat seal of the packaging article, so that upon initiating first and second linear tears across the first and second lay-flat sides of the packaging article from the second tear initiator to the opposite edge of the packaging article, with the first and second tears being manually-propagated across a width of the packaging article, and thereafter initiating third and fourth linear tears down the first and second lay-flat sides of the packaging article from the first tear initiator, with the third and fourth tears being manually-propagated down the length of the packaging article to the opposite edge of the packaging article, a first unrestrained corner flap is produced on the first lay-flat side of the packaging article, and a second unrestrained corner flap is produced on the second lay-flat side of the packaging article, with the unrestrained corner flaps being capable of curling all the way back to a diagonal line extending from a torn end of the first heat seal to a torn end of the second heat seal, thereby exposing the product within the chamber of the packaging article. 